The Collaborative International Dictionary of English v.0.48:
Fer-de-lance \Fer`-de-lance"\, n. [F., the iron of a lance, lance head.] (Zool.) A large, venomous serpent (Trigonocephalus lanceolatus) of Brazil and the West Indies. It is allied to the rattlesnake, but has no rattle. [1913 Webster]WordNet (r) 3.0 (2006):
fer-de-lance n 1: large extremely venomous pit viper of Central America and South America [syn: fer-de-lance, Bothrops atrops]