The Collaborative International Dictionary of English v.0.48:
Pea-jacket \Pea"-jack`et\, Pea jacket \Pea" jack`et\ Pea jacket \Pea" jack`et\, n. [Prob. fr. D. pij, pije, a coat of a coarse woolen stuff.] A thick loose double-breasted woolen jacket, or coat, commonly worn by sailors in cold weather. Syn: pea coat, peacoat, pea jacket. [1913 Webster+ WordNet 1.5]