Definitions for pea jacket
Random House Webster's College Dictionary
a short, double-breasted coat of navy-blue wool, worn by seamen.
any jacket or short coat resembling this.
Ref: Also called peacoat.
Origin of pea jacket:
1715–25, Amer.; pea, var. sp. of pay, pee, pie coat of coarse woolen cloth (late ME pee, pey, pie; akin to D pij, dial. Fris pey, dial. Sw paje); perh. modeled on Fris (N Fris) pijekkat
pea jacket, peacoat(noun)
a sailor's heavy woolen double-breasted jacket