Arcing is the jumping of current over an air gap caused by poor or damaged electrical connections in a circuit that can become an electrical fire hazard

Argon is a gas filled between glass panes to slow heat transfer through a window

An axis is a fixed reference line often for a measurement

Back rolling is the process of applying a roller over a brushed or sprayed area to add a uniform texture

Backer rod is a foam strip used to fill larger cracks prior to caulking

The base section is the fixedladder section that does not move on an extension ladder. It remains planted to the ground and supports the fly section

The base plate of a saw is a flat saw surface that makes contact with the material being cut and helps keeps the tool under control

A basin is a bowl for washing which is typically attached to a wall and having faucets connected to a water supply and a drain line for removing wastewater 

A battery pack is a portable and rechargeable power source for cordless tools

A bead is a line of caulk applied to a joint or seam