From The Collaborative International Dictionary of English v.0.48 [gcide]:
Cowcatcher \Cow"catch`er\ (-k?ch`?r), n.
A strong inclined frame, usually of wrought-iron bars, in
front of a locomotive engine, for catching or throwing off
obstructions on a railway, as cattle; the pilot. [U.S.]
Syn: fender, buffer, pilot.
[1913 Webster]
From WordNet (r) 3.0 (2006) [wn]:
cowcatcher
n 1: an inclined metal frame at the front of a locomotive to
clear the track [syn: fender, buffer, cowcatcher,
pilot]