Steam  —n. 1 a gas into which water is changed by boiling. B condensed vapour formed from this. 2 a power obtained from steam. B colloq. Power or energy. —v. 1 a cook (food) in steam. B treat with steam. 2 give off steam. 3 a move under steam power. B (foll. By ahead, away, etc.) Colloq. Proceed or travel fast or with vigour. 4 (usu. Foll. By up) a cover or become covered with condensed steam. B (as steamed up adj.) Colloq. Angry or excited. [old english]