The Collaborative International Dictionary of English v.0.48:

Swab \Swab\, v. t. [imp. & p. p. Swabbed; p. pr. & vb. n.
   Swabbing.] [See Swabber, n.]
   To clean with a mop or swab; to wipe when very wet, as after
   washing; as, to swab the desk of a ship. [Spelt also swob.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Swab \Swab\, n. [Written also swob.]
   1. A kind of mop for cleaning floors, the desks of vessels,
      etc., esp. one made of rope-yarns or threads.
      [1913 Webster]

   2. A bit of sponge, cloth, or the like, fastened to a handle,
      for cleansing the mouth of a sick person, applying
      medicaments to deep-seated parts, etc.
      [1913 Webster]

   3. (Naut.) An epaulet. [Sailor's Slang] --Marryat.
      [1913 Webster]

   4. A cod, or pod, as of beans or pease. [Obs.] --Bailey.
      [1913 Webster]

   5. A sponge, or other suitable substance, attached to a long
      rod or handle, for cleaning the bore of a firearm.
      [1913 Webster]

WordNet (r) 3.0 (2006):

swab
    n 1: implement consisting of a small piece of cotton that is
         used to apply medication or cleanse a wound or obtain a
         specimen of a secretion
    2: cleaning implement consisting of absorbent material fastened
       to a handle; for cleaning floors [syn: swab, swob, mop]
    v 1: wash with a swab or a mop; "swab the ship's decks" [syn:
         swab, swob]
    2: apply (usually a liquid) to a surface; "dab the wall with
       paint" [syn: dab, swab, swob]

Moby Thesaurus II by Grady Ward, 1.0:

65 Moby Thesaurus words for "swab":
   air-dry, anhydrate, bake, baptize, bath, bathe, blot, brush, burn,
   cure, dehumidify, dehydrate, desiccate, douche, drain, dry,
   evaporate, exsiccate, fire, flush, flush out, gargle, holystone,
   insolate, irrigate, kiln, lather, launder, lave, mop, mop up,
   mummify, parch, rinse, rinse out, ritually immerse, rub, scorch,
   scour, scrub, scrub up, sear, shampoo, shower, shrivel, sluice,
   sluice out, smoke, soak up, soap, sponge, sun, sun-dry, syringe,
   toivel, torrefy, towel, tub, wash, wash out, wash up, weazen, wipe,
   wither, wizen



The Jargon File (version 4.4.7, 29 Dec 2003):

swab
 /swob/

    [From the mnemonic for the PDP-11 ?SWAp Byte? instruction, as
    immortalized in the dd(1) option conv=swab (see dd)]

    1. vt. To solve the NUXI problem by swapping bytes in a file

    2. n. The program in V7 Unix used to perform this action, or anything
    functionally equivalent to it. See also big-endian, little-endian, 
    middle-endian, bytesexual.


The Free On-line Dictionary of Computing (30 December 2018):

swab

   /swob/ The PDP-11 swap byte instruction mnemonic, as
   immortalised in the dd option "conv=swab".

   1. To solve the NUXI problem by swapping bytes in a file.

   2.  The program in V7 Unix used to perform this action, or
   anything functionally equivalent to it.

   See also big-endian, little-endian, middle-endian,
   bytesexual.

   [Jargon File]