The Collaborative International Dictionary of English v.0.48:
Gnawer \Gnaw"er\, n. 1. One who, or that which, gnaws. [1913 Webster] 2. (Zool.) A rodent. [1913 Webster]WordNet (r) 3.0 (2006):
gnawer n 1: relatively small placental mammals having a single pair of constantly growing incisor teeth specialized for gnawing [syn: rodent, gnawer]