Wordnet 3.0
NOUN (1)
1. 
 small destroyer that was the forerunner of modern destroyers; 
 designed to destroy torpedo boats; 
The Collaborative International Dictionary of English v.0.48:
Torpedo-boat destroyer \Tor*pe"do-boat` de*stroy"er\
   A larger, swifter, and more powerful armed type of torpedo
   boat, originally intended principally for the destruction of
   torpedo boats, but later used also as a more formidable
   torpedo boat.
   [Webster 1913 Suppl.]
WordNet (r) 3.0 (2006):
torpedo-boat destroyer
    n 1: small destroyer that was the forerunner of modern
         destroyers; designed to destroy torpedo boats