The Collaborative International Dictionary of English v.0.48:
Drummer \Drum"mer\, n.
1. One whose office is to best the drum, as in military
exercises and marching.
2. One who solicits custom; a commercial traveler. [Colloq.
3. (Zool.) A fish that makes a sound when caught; as:
(a) The squeteague.
(b) A California sculpin.
4. (Zool.) A large West Indian cockroach (Blatta gigantea)
which drums on woodwork, as a sexual call.