The Collaborative International Dictionary of English v.0.48:

Washerman \Wash"er*man\, n.; pl. Washermen.
   A man who washes clothes, esp. for hire, or for others.
   [1913 Webster]

WordNet (r) 3.0 (2006):

washerman
    n 1: operates industrial washing machine [syn: washerman,
         laundryman]