Swab means to clean or wipe something using a small piece of absorbent material, usually on the end of a stick. When a nurse swabs your arm with alcohol before giving you a shot, she's wiping it clean to kill germs. Sailors used to swab the deck by mopping the wooden floors of their ships to keep them clean and prevent rot.

The word also refers to the tool itself: a cotton swab (like a Q-tip) is perfect for cleaning small spaces or applying medicine to a tiny cut. Doctors take throat swabs when testing for strep throat, gently wiping the back of your throat with a long cotton-tipped stick to collect a sample.

In the old days of sailing ships, swab was also slang for a lowly sailor whose job included the unglamorous work of mopping the decks. Today, doctors and scientists swab surfaces to test for bacteria or viruses, and archaeologists carefully swab ancient artifacts to clean them without causing damage. Whether you're swabbing a skinned knee or a laboratory surface, you're using gentle wiping motions to clean or collect something important.