swab also swob 
(swŏb)
(swŏb)n.
1.
a. A small piece of absorbent material attached to the end of a stick or wire and used for cleansing a surface, applying medicine, or collecting a sample of a substance.
b. A sample collected with a swab.
2. A sponge or patch of absorbent material used to clean the bore of a firearm or cannon.
3. A mop used for cleaning floors or decks.
4. Slang A sailor.
5. Slang A lout.
tr.v. swabbed, swab·bing, swabs also swobbed or swob·bing or swobs
1. To use a swab on.
2. To clean with a swab.
3. To collect a sample from (a person, for example) using a swab.
[Back-formation from swabber, mop for a ship's deck (from obsolete Dutch *zwabber, from zwabben, to mop) or from obsolete Dutch swabbe, mop (from Middle Dutch).]