The Collaborative International Dictionary of English v.0.48:

Scrubber \Scrub"ber\ (skr[u^]b"b[~e]r), n.
   1. One who, or that which, scrubs; esp., a brush or machine
      used in scrubbing.
      [1913 Webster +PJC]

   2. (Gas Manuf.) A gas washer. See under Gas.
      [1913 Webster]

   3. (Manufacturing) a device for removing pollutants from a
      gas stream, especially for removing sulfur oxides from
      processes burning coal or oil.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Scrubber \Scrub"ber\ (skr[u^]b"b[~e]r), n.
   1. a stunted or emaciated steer.
      [PJC]

   2. A person who lives in the bush. [Australian]
      [PJC]

   3. A domesticated animal which has escaped and lives wild in
      the bush. [Australian]
      [PJC]

WordNet (r) 3.0 (2006):

scrubber
    n 1: a worker who uses a scrub brush to clean a surface (usually
         a floor or deck)
    2: a brush with short stiff bristles for heavy cleaning [syn:
       scrub brush, scrubbing brush, scrubber]
    3: a purifier that removes impurities from a gas