The Collaborative International Dictionary of English v.0.48:

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. skrubbe, 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.
   [1913 Webster]

WordNet (r) 3.0 (2006):

scrubbing
    n 1: the act of cleaning a surface by rubbing it with a brush
         and soap and water [syn: scrub, scrubbing, scouring]