Abrasive is different grades of rough grit applied to a paper backing to remove material when sanding. Abrasives range from coarse to fine and have numbers to indicate their roughness with lower numbers meaning coarser grits and higher numbers meaning finer

ABS is black plastic pipe used in plumbing for drain, waste, and vent pipes.

The actuator is the part of a caulk gun that moves the plunger forward

Adhesion is the ability for a material to stick to a surface

An adjustable wrench is a tool for tightening hex nuts and bolts of various sizes

An Arc Fault Circuit Interrupter  or AFCI is a specialelectrical safety device in the form of an outlet or breaker that shuts the power down when arcing conditions are detected

To air dry is the hardening process of a material that depends on the air or solvent in the mix to evaporate completely

An air exhaust port on a nail gun is the location where air escapes after the tool is fired

An air filter is a replaceable device for cleaning air as it enters the compressor

An air inlet port is the location on a pneumatic tool where pressurized air enters the tool