Source : Webster's Revised Unabridged Dictionary (1913)

Scrub \Scrub\, a.
   Mean; dirty; contemptible; scrubby.

         How solitary, how scrub, does this town look!
                                                  --Walpole.

         No little scrub joint shall come on my board. --Swift.

   {Scrub game}, a game, as of ball, by unpracticed players.

   {Scrub race}, a race between scrubs, or between untrained
      animals or contestants.

Scrub \Scrub\, v. i.
   To rub anything hard, especially with a wet brush; to scour;
   hence, to be diligent and penurious; as, to scrub hard for a
   living.

Scrub \Scrub\, n.
   1. One who labors hard and lives meanly; a mean fellow. ``A
      sorry scrub.'' --Bunyan.

            We should go there in as proper a manner possible;
            nor altogether like the scrubs about us.
                                                  --Goldsmith.

   2. Something small and mean.

   3. A worn-out brush. --Ainsworth.

   4. A thicket or jungle, often specified by the name of the
      prevailing plant; as, oak scrub, palmetto scrub, etc.

   5. (Stock Breeding) One of the common live stock of a region
      of no particular breed or not of pure breed, esp. when
      inferior in size, etc. [U.S.]

   {Scrub bird} (Zo["o]l.), an Australian passerine bird of the
      family {Atrichornithid[ae]}, as {Atrichia clamosa}; --
      called also {brush bird}.

   {Scrub oak} (Bot.), the popular name of several dwarfish
      species of oak. The scrub oak of New England and the
      Middle States is {Quercus ilicifolia}, a scraggy shrub;
      that of the Southern States is a small tree ({Q.
      Catesb[ae]i}); that of the Rocky Mountain region is {Q.
      undulata}, var. Gambelii.

   {Scrub robin} (Zo["o]l.), an Australian singing bird of the
      genus {Drymodes}.

Scrub \Scrub\ (skr[u^]b), v. t. [imp. & p. p. {Scrubbed}
   (skr[u^]bd); p. pr. & vb. n. {Scrubbing}.] [OE. scrobben,
   probably of Dutch or Scand. origin; cf. Dan. sckrubbe, Sw.
   skrubba, D. schrobben, LG. schrubben.]
   To rub hard; to wash with rubbing; usually, to rub with a wet
   brush, or with something coarse or rough, for the purpose of
   cleaning or brightening; as, to scrub a floor, a doorplate.

Scrub \Scrub\, n.
   1. Vegetation of inferior quality, though sometimes thick and
      impenetrable, growing in poor soil or in sand; also,
      brush. See {Brush}, above.

Source : WordNet®

scrub
     adj : (of domestic animals) not selectively bred
     [also: {scrubbing}, {scrubbed}]

scrub
     v 1: clean with hard rubbing; "She scrubbed his back" [syn: {scour}]
     2: wash thoroughly; "surgeons must scrub prior to an operation"
        [syn: {scrub up}]
     [also: {scrubbing}, {scrubbed}]

scrub
     n 1: dense vegetation consisting of stunted trees or bushes [syn:
           {chaparral}, {bush}]
     2: the act of cleaning a surface by rubbing it with a brush and
        soap and water [syn: {scrubbing}, {scouring}]
     [also: {scrubbing}, {scrubbed}]