The Collaborative International Dictionary of English v.0.48:

Lasher \Lash"er\, n.
   One who whips or lashes.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Lasher \Lash"er\, n.
   1. A piece of rope for binding or making fast one thing to
      another; -- called also lashing.
      [1913 Webster]

   2. A weir in a river. [Eng.] --Halliwell.
      [1913 Webster]

WordNet (r) 3.0 (2006):

lasher
    n 1: a driver who urges the animals on with lashes of a whip