the.com/swatter

means A tool, usually a flexible mesh or plastic paddle on a handle, used for killing insects by striking them.

from A straightforward agent noun from 'swat' plus '-er' — the swatter is simply 'the thing that swats.' Swat itself emerged in 19th-century American English as a dialect variant of 'squat,' meaning to hit or slap something flat down with force. The classic woven-wire fly swatter became a household fixture in the early 1900s, around the same era public health campaigns were urging people to kill flies as disease carriers — practical hygiene breeding a very ordinary little weapon.