Accordion shutter
A shutter whose connected sections fold to the sides when stored and extend across the opening for use.
WINDOW DICTIONARY · A HOMEOWNER’S REFERENCE
Window and Door
Dictionary
Clear explanations for the words you hear when planning new windows and doors. Explore 214 terms covering styles, parts, trim, hardware, glass, storm protection, and installation.
All terms, A–Z
Active panel
The panel normally used for opening and closing in a multi-panel assembly.
Air leakage (AL)
Measured airflow through a closed product under specified test conditions; lower values indicate less leakage.
Allowance
A budget amount reserved for a selection or item not fully specified when the proposal is prepared.
Aluminum
A metal used for slim, rigid frames; thermal performance depends on the complete frame design.
Anchor
A component transferring loads from the assembly into suitable supporting construction.
Annealed glass
Glass without the strengthening treatment used for tempered or heat-strengthened glass.
Anodized finish
An electrochemically formed protective finish on aluminum.
Anti-lift device
A feature intended to limit lifting a sliding panel out of its track.
Apron
Trim installed beneath an interior window stool.
Architrave
Decorative trim around an opening, sometimes referring to a prominent top casing.
Argon fill
Argon gas used between glass panes to reduce heat transfer.
Astragal
A member at the meeting edge of paired doors that helps cover or seal the joint.
Awning window
A top-hinged window that opens outward from the bottom.
Backband
An additional trim profile around the outer edge of casing.
Backer rod
A compressible rod placed in a joint to support sealant and help control its shape and depth.
Backset
The distance from a door edge to the center of its handle or lock preparation.
Balance
A mechanism that offsets sash weight in a hung window.
Barn door
A surface-mounted sliding door carried on a track outside the wall opening.
Bay window
An assembly that projects beyond the wall, usually with a broad center window and angled side windows.
Bifold door
Connected panels that fold together as the opening is cleared; used in both interior and exterior systems.
Block-and-tackle balance
A sash-support mechanism using springs, cords, and pulleys.
Bow window
A projecting group of windows arranged in a gentle curve.
Brickmould
An exterior trim profile used around windows and doors, including on walls without brick.
Buck
Framing or supporting material around an opening used as part of the attachment and installation design.
Casement window
A side-hinged window that swings open, often operated by a crank.
Casing
Finish trim surrounding a window or door where its frame meets the wall.
Caulk
A common name for joint-sealing material; select the actual product by compatibility and application requirements.
Change order
A written agreement documenting a change to the work, price, or schedule.
Cladding
A protective exterior covering over another material, such as aluminum over wood.
Clerestory window
A window placed high on a wall to bring light into a room.
Composite
A material combining different constituents; its properties depend on the particular formulation.
Condensation
Moisture forming when a surface is below the surrounding air's dew point.
Constant-force balance
A sash-support mechanism using a coiled metal spring.
Cure time
The time a material needs to develop its specified properties; conditions can affect it.
Cyclic pressure testing
Repeated positive and negative pressure loading used in certain storm-performance evaluations.
Deadbolt
A locking bolt that extends into a strike and does not rely on a spring latch.
Desiccant
Moisture-absorbing material used inside the edge system of an IGU.
Design pressure (DP)
A pressure value used in specifying a product's wind-load performance; it is not a direct hurricane category or wind-speed label.
Door closer
Hardware that returns a door toward its closed position.
Door leaf
One individual moving door panel.
Door sweep
A strip along the door bottom that helps close the gap above the threshold.
Double entry door
Two door leaves in one entry assembly, often with one active and one secondary leaf.
Double-hung window
A window whose upper and lower sashes both move vertically.
Double-pane glass
Two panes assembled with a space between them; different from two movable sashes.
Drip cap
A projecting flashing or trim feature that helps shed water above an opening.
Dutch door
A door divided horizontally so the upper and lower portions can operate separately.
Edge distance
The distance between an anchor and an edge of its supporting material; required distances depend on the design.
Egress window
A common name for a window intended to serve emergency escape and rescue; the actual clear opening and placement must meet applicable requirements.
Embedment
The depth a fastener or anchor engages the required supporting material.
ENERGY STAR
An efficiency certification program; qualification depends on the applicable product and climate criteria.
Entry door
An exterior door used for entering a building, often the main front door.
Fastener schedule
The specified fastener type, quantity, spacing, and placement for an installation.
Fenestration
A collective term for building openings and their window, door, and skylight systems.
Fiberglass
A glass-fiber-reinforced material used in door skins, frames, and other components.
Fixed window
A window that does not open for ventilation.
Flange
A projecting edge used for attachment, coverage, or joining, depending on the product.
Flashing
Materials arranged to direct water away from vulnerable joints and openings.
Flashing tape
A membrane tape used to connect water-management surfaces around an opening as part of a compatible system.
Flush bolt
A recessed bolt often used to secure the secondary leaf of double doors.
Flush door
A door with a mostly flat, smooth face.
Frame
The surrounding assembly that supports a window sash or door leaf.
French doors
Paired hinged doors, commonly with glass panels; one or both leaves may operate.
Friction stay
Hinged support hardware using friction to help position an opening sash.
Full-frame replacement
Removal of the existing frame and replacement with a complete new assembly.
Garden window
A projecting glass enclosure with a shelf-like base, often used for plants above a kitchen sink.
Glazing
The glass in an opening, or the work of fitting it into the frame.
Glazing bead
A removable strip that helps retain glass within its frame or sash.
Glazing gasket
A shaped sealing component used around glass within an assembly.
Grille
A decorative grid that gives glass a divided appearance.
Grilles between glass (GBG)
Decorative bars located inside a sealed glass unit rather than on its exposed surfaces.
Handing
The specified orientation of hinges and swing; naming conventions vary, so confirm with a drawing and the supplier.
Head
The top horizontal part of a window or door frame.
Head flashing
Flashing above an opening that directs water away from the top joint.
Header
The structural member spanning above an opening and carrying loads around it; different from the window's frame head.
Heat-strengthened glass
Glass given a heat treatment that increases strength; it is not automatically a safety-glazing substitute.
Hinge
Hardware allowing a panel to swing about an edge.
Hollow-core door
An interior door with lightweight internal construction rather than a solid core.
Hopper window
A bottom-hinged window that typically tilts inward from the top.
Hurricane fabric
A purpose-made flexible opening-protection system used with its specified attachments; ordinary shade fabric is not equivalent.
HVHZ
High-Velocity Hurricane Zone, the Florida code designation associated with Miami-Dade and Broward counties; do not assume it describes every Florida coastal location.
Impact-rated
Tested and rated for specified impact conditions as a complete assembly; check the exact product and approved installation.
Inactive panel
A secondary panel that normally stays secured but may open after separate bolts or locks are released.
Insert replacement
A replacement unit installed within a retained existing frame where conditions and product instructions allow.
Inspection
A review of specified work; a homeowner walkthrough and an official permit inspection are different activities.
Insulating glass unit (IGU)
A sealed assembly of glass panes separated by one or more spaces.
Inswing
A door or sash that opens toward the interior.
Interlayer
The bonding layer between sheets in laminated glass.
Interlock
A profile that engages an adjacent sliding panel when closed.
Jack stud
A shorter stud that supports a header beside an opening; also called a trimmer stud.
Jalousie window
A window with rows of adjustable slats that pivot together for ventilation.
Jamb
A frame member at an opening; side jambs are vertical, and a head jamb is at the top.
Jamb extension
Material added to extend the frame depth to meet the finished wall surface.
Keeper
The part engaged by a lock or latch to secure the assembly.
Kerf
A narrow groove; some weatherstripping fits into a kerf in the frame.
King stud
A full-height framing stud beside an opening in a framed wall.
Krypton fill
Krypton gas used in some insulating glass spaces, often in narrower cavities.
Laminated glass
Glass layers bonded to an interlayer that helps retain fragments when broken; hurricane performance requires a rated complete assembly.
Large-missile impact
An impact-test category using a specified larger projectile; the test standard defines the details.
Latch
A mechanism that holds a door closed, typically released by a handle or lever.
Lead time
The expected interval between ordering and availability or delivery; it is not necessarily the installation date.
Level
Horizontally aligned.
Lintel
A supporting member above an opening, often in masonry construction.
Lite (light)
A glazed area in a window or door; usage varies between product descriptions.
Lock cylinder
The keyed component that operates a lock mechanism.
Louvered door
A door with angled slats that permit airflow, commonly used for closets or utility spaces.
Low-E coating
A low-emissivity coating that changes radiant heat transfer; coating choices have different solar and light properties.
Low-expansion foam
A foam sealant formulated for controlled expansion; use only products and application methods suitable for the opening.
Low-iron glass
Glass made with reduced iron content to lessen its green tint.
Manufacturer warranty
The manufacturer's written coverage, conditions, exclusions, and claim process for its product.
Meeting rail
The horizontal sash members that come together when a hung window is closed; also called check rails.
Meeting stile
The adjacent vertical edges where two panels or door leaves meet.
Miter
An angled joint, commonly used where casing pieces meet at a corner.
Mortise lock
A lock body fitted into a pocket cut into the door edge.
Mullion
A member between adjoining window or door units; its structural role depends on the assembly.
Multi-slide door
A system with several sliding panels that stack or slide into a pocket, depending on its design.
Multipoint lock
A mechanism securing a window or door at several locations through one operating action.
Muntin
A narrow member separating individual panes in a traditional divided-light design.
Nailing fin
A flange around certain units used in the specified attachment and flashing approach; its name does not prescribe the fasteners.
Negative pressure
Suction acting outward on a building surface or assembly.
Net clear opening
The unobstructed opening available when a window or door is fully open, not its overall frame size.
NFRC
National Fenestration Rating Council, an organization providing standardized energy-performance ratings for windows, doors, and skylights.
Nominal size
A convenient labeled size that may differ from actual dimensions; verify the product drawings before ordering.
Notice of Acceptance (NOA)
A Miami-Dade product-approval document; its limitations and installation details matter for the proposed application.
Obscure glass
Glass that reduces clear visibility for privacy, often through texture or a translucent appearance.
Opening protection
A system intended to protect vulnerable openings, such as impact-rated windows or suitable shutters.
Operator
The mechanism that moves a window, often a crank and linkage.
Outdoor-indoor transmission class (OITC)
A sound-isolation rating that gives attention to lower-frequency exterior noise, such as transportation noise.
Outswing
A door or sash that opens toward the exterior.
Palladian window
A composition with an arched central window flanked by two narrower rectangular windows.
Pane
An individual sheet of glass.
Panel door
A door with recessed or raised panels framed by rails and stiles.
Pass-through window
An opening window used to connect serving areas, such as a kitchen and patio counter.
Patio door
A door connecting indoor living space to a patio, deck, or yard.
Permit
Authorization from the relevant local authority for work requiring it; requirements depend on the project and location.
Picture window
A fixed window selected to frame a view and admit daylight.
Pivot door
A door that turns on pivots at the top and bottom rather than conventional side hinges.
Pivot shoe
A component connecting a tilting sash to its balance mechanism.
Plumb
Vertically aligned.
Pocket door
A door that slides into a concealed wall cavity.
Positive pressure
Pressure pushing against a building surface or assembly.
Powder coating
A factory-applied finish formed by curing a dry coating onto a surface.
Prehung door
A door supplied already fitted on hinges within its frame.
Product approval
Documentation identifying approved product configurations and conditions of use; verify it applies to the proposed size and installation.
Punch list
A written list of remaining corrections or finishing items before project closeout.
R-value
Resistance to heat flow. Compare windows using whole-product ratings rather than a glass-only insulation claim.
Radius window
A window incorporating a curved section, such as a half-circle top.
Rail
A horizontal member in a sash or door panel.
Retrofit
An alteration or upgrade to an existing building; the term alone does not define what the installer removes.
Return
A finished surface turning back toward the frame, such as a drywall or stucco return.
Reveal
The visible offset or exposed edge between adjoining frame and trim surfaces.
Roll-down shutter
A shutter that travels in side tracks and stores in a housing above the opening.
Roller
A wheel assembly supporting and moving a sliding panel along its track.
Roof window
A roof-mounted window designed for operation and use within the manufacturer's specified reach and installation conditions.
Rough opening
The opening in the wall structure prepared to receive the window or door assembly.
Safety glazing
Glazing meeting applicable human-impact safety requirements for its intended location.
Sash
The framed portion of a window that holds its glass; it may move or remain fixed.
Sash lock
Hardware securing a sash in its closed position.
Scope of work
The description of what a project includes, such as removal, installation, trim, repairs, and disposal.
Screen door
A door with mesh panels that provides ventilation while helping keep insects out.
Screen spline
The flexible strip that holds insect mesh in the groove of a screen frame.
Seal failure
Loss of an IGU's edge-seal integrity; persistent moisture between panes is a common symptom.
Sealant
A flexible material used to seal compatible joints against air or water movement.
Shim
A thin spacer used to position and support an assembly without distorting it.
Shingle lap
Overlapping water-management layers so the upper layer drains onto the exterior face of the lower layer.
Sidelight
A narrow glazed section beside an entry door.
Sill
The bottom of a window frame or opening, designed with the surrounding details to manage water.
Sill pan
A water-management detail beneath an opening designed to collect and direct incidental water outward.
Simulated divided light (SDL)
Bars applied to glass to resemble traditional divided panes; an internal spacer may also be used.
Single-hung window
A window with a movable lower sash and a stationary upper sash.
Skylight
A glazed opening in the roof that may be fixed or venting.
Slab door
The door leaf by itself, supplied without a complete installed frame assembly.
Sliding glass door
A glazed door system with panels that move sideways on tracks.
Sliding window
A window with one or more sashes that move horizontally along tracks; also called a glider.
Small-missile impact
An impact-test category using specified small projectiles; it does not describe every possible storm hazard.
Solar heat gain coefficient (SHGC)
The fraction of solar heat admitted through a product; lower values mean less solar heat gain.
Solid-core door
A door with a dense core, often selected for a heavier feel and improved sound separation compared with hollow-core designs.
Sound transmission class (STC)
A laboratory rating of sound reduction across a defined range of frequencies; higher generally means more reduction.
Spacer
A component keeping the panes of an IGU the required distance apart around its perimeter.
Specialty-shape window
A window made in a shape such as a triangle, circle, or trapezoid.
Spiral balance
A sash-support mechanism using a spring and spiral rod.
Square
Having correctly aligned right-angle corners; installers may compare diagonals as part of checking an assembly.
Steel door
A door with steel faces, often surrounding an insulating core.
Stile
A vertical member in a sash or door panel.
Stool
The interior horizontal ledge at the bottom of a window, often casually called the interior sill.
Stop
A strip or frame feature limiting movement or retaining a component, depending on its location.
Storm door
A secondary exterior door with glass or screen panels; it is not automatically hurricane-rated.
Storm panel
A removable protective panel secured over an opening using its designed mounting system.
Storm window
An additional window layer fitted over an existing window; the name alone does not mean hurricane-impact protection.
Strike plate
The plate on a frame that receives a latch or bolt.
Substrate
The surface or underlying material receiving a fastener, coating, adhesive, or sealant.
Tempered glass
Heat-treated safety glass designed to break into small fragments; tempering alone does not establish hurricane-impact resistance.
Thermal break
A less-conductive separator that interrupts heat flow through a metal frame.
Threshold
The bottom member of a doorway that is crossed when entering.
Tilt latch
A release that allows a compatible sash to tilt inward, usually for cleaning.
Tilt-and-turn window
A window with hardware that allows either an inward tilt or an inward side swing.
Tinted glass
Glass with coloration that changes light transmission and solar characteristics.
Track
The channel or running surface that guides a sliding component.
Transom window
A window positioned above a door or another window; it may be fixed or operable.
Triple-pane glass
Three panes assembled with two intervening spaces.
True divided light
A design using separate individual glass panes divided by framing members.
Tubular daylighting device
A roof collector and reflective tube that carry daylight to an interior diffuser.
U-factor
A heat-transfer rating: a lower value indicates better insulation under the rating conditions.
Unit size
The actual dimensions of the manufactured assembly, which differ from the required rough opening.
Vinyl (uPVC)
A rigid plastic used for many window frames and components.
Visible transmittance (VT)
The fraction of visible light transmitted through a product; higher values mean more visible light passes through.
Warm-edge spacer
A spacer designed to reduce heat transfer at the perimeter of an insulating glass unit.
Water-resistive barrier (WRB)
A wall layer that helps manage water behind the exterior cladding.
Weatherstripping
Flexible material that seals the meeting surfaces of movable components.
Weep hole
A drainage outlet in a frame or track; it should not be covered with sealant.
Windborne debris
Objects carried by wind that can strike windows, doors, and other building components.
Window opening control device (WOCD)
A device that limits opening until released as designed; it is different from an ordinary insect screen or security lock.
Wood door
A door made with wood components; construction and required finish maintenance vary.
Workmanship warranty
Coverage offered for installation work; terms are separate from the product manufacturer's warranty.
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