Lewis & Short

pīsum, i (late Lat. collat. form pīsa, ae, f., Apic. 5, 4; Pall. 11, 14), n., = πισόν, a species of leguminous plant, pease, the pea, Col. 2, 10, 4; Plin. 18, 12, 31, § 123; 18, 12, 33, § 125.