amps (amperes) A unit of measurement for the speed of the flow of electrons in electric current.

assembly A set of components before they’re put together.

bleeding Removing the air from a hot water heating system by releasing air from individual radiator valves. This provides consistent heat throughout the system.

boiler The heating plant for systems that heat and move water or steam through pipes.

caulk A material used to create a watertight seal between two adjoining surfaces.

chase A channel in the wall of a structure that holds pipes or wires, providing space for them to run from room to room or floor to floor.

cheesecloth A light, gauzy fabric originally used to strain and hold cheese. When it comes to home repair, cheesecloth is a great applicator for various liquids.

circuit A loop through which electrical current can flow, beginning and ending at the same point. Household electrical circuits begin and end at the electrical panel, which receives its current from electric utility service lines that enter at the top of the panel.

circuit breaker A device that stops the flow of electricity in a circuit if there is too much current for safe operation. Both the toggle switches and the fuses used in the two types of service panels act as circuit breakers, but only the toggle switch type are commonly referred to as circuit breakers.

conductor A medium that allows heat, electricity, light, or sound to pass through or along it. Copper wire is a good conductor of electrical current.

drywall The most common type of base wall material. It is made by sandwiching a gypsum core, which is fire resistant, between layers of paper. Also known as Sheetrock, wallboard, or gypsum board, this material is also made in a water resistant variety for use in damp areas.

electricity The flow of electrons through a conductor.

fenestration The architectural term that refers to the design and placement of windows in a building.

furnace The heating plant for forced-air systems—the majority of systems in the U.S—that heat air and then move it, by means of a blower, through a system of ducts.

furring strips Thin, narrow pieces of wood used to provide backing to support a finished surface.

filament A slender strand of fiber or other material. The thin wire that is the light-producing element of a bulb when electricity passes through it, and the element that emits electrons in a vacuum tube when current is passed through it, are also known as filaments.

gasket A material that creates a seal between two surfaces—for example, a door and its opening—that prevents the passage of liquid or gas. Many home appliances have rubber gaskets around their doors.

gauge The sizing system for the diameter of wire. The smaller the gauge number, the larger the diameter of the wire.

grade The level at which the ground meets a structure.

ground fault circuit interrupter (GFCI) A device used in code-compliant electrical receptacles near water sources. The GFCI almost instantly cuts power to a circuit if it detects a leakage of electric current.

grounding When he or she grounds your electrical system, the electrician has connected it to the earth. Grounding provides a safe path for any loose current—from a defective fixture or appliance, or exposed wire touching metal somewhere in the system.

grout Thin mortar used to fill gaps between tiles or other surfacing materials.

grout saw a small hand tool that looks like a knife with an offset handle. It’s great for cutting between tiles so that grout can be easily removed, without scratching adjacent tiles.

header The top horizontal part of a door or window frame.

ionizing filter An air-cleaning device that gives tiny particles a charge that makes them stick to the surface of the filter until they are cleaned off.

jamb The vertical part of the frame of an opening, either a window or a door.

joint In carpentry, the intersection of two pieces of wood. There are many different kinds of wood joints.

joist The framing that supports a floor or ceiling.

kilowatt hour (kWh) A unit of energy equivalent to one kilowatt (1 kW) of power used for one hour (1 h) of time.

lath A framework of thin wood strips, or, more recently, wire mesh, that is used as the foundation for plaster or sometimes for tile.

load The amount of electrical current that is drawn from a source. An excessive load on a household circuit will cause a fuse to blow or a circuit breaker to trip to “off.”

mastic A flexible cement used as an adhesive for affixing tile to an underlying surface.

mortise A hole or slot cut into wood or other material, so that a projecting piece (called a tenon) can be precisely inserted. Mortise-and-tenon joints are a very sturdy joinery technique used in woodworking and carpentry.

packing A material, often string, that is used like a washer in the assembly of a compression faucet.

pneumatic A tool or machine that is operated by compressed air.

rafters The sloping supporting timbers or boards that run from the ridge to the edge of the roof.

rails The horizontal framing pieces of a window sash or door.

ridge The long, straight center timber at the joint between the sloping sides of a gabled roof.

sash The part of a window that holds one or more panes of glass or other transparent or translucent material.

shim A thin, wedge-shaped piece of wood, metal, plastic, or cardboard. It’s used to help position something properly by filling a gap, or to protect a surface from something that may scratch or mar it.

stiles The vertical framing pieces of a window sash or door.

sidelight A window positioned next to a door.

solvent A substance in which other substances are dissolved.

spirit level An instrument designed to indicate whether a surface is level (horizontal measure) or plumb (measured vertically).

spline A piece of wood, metal, or plastic that is used as a connecting or framing piece between two sections of material. Spline can be used to hold a screen in its surrounding frame; the material that frames caning in a chair seat where it meets the wood or metal part of the seat is also known as spline.

spline tool A hand tool for installing spline; it has a wheel at each end. One wheel has a convex (∪) rim, for pushing the screen into the spline channel; the other wheel has a concave (∩) rim, for pushing the spline down over the mesh and into the channel.

supply stops On/off controls found along household utility supply lines, managing the flow of gas or water to individual fixtures and appliances.

tempered glass Glass that has been heated and cooled repeatedly in a controlled environment to give it more strength than conventional, single-layer window glass.

vise A tool with two jaws, closed by a screw or a lever to hold objects immobile.

volt A measure of the force with which electrons move in electrical current.

watt A measure of electrical output.