Watch  —v. 1 keep the eyes fixed on. 2 keep under observation; follow observantly. 3 (often foll. By for) be in an alert state; be vigilant. 4 (foll. By over) look after; take care of. —n. 1 small portable timepiece for carrying on the wrist or in a pocket. 2 state of alert or constant observation or attention. 3 naut. A usu. Four-hour spell of duty. B (in full starboard or port watch) each of the halves into which a ship's crew is divided to take alternate watches. 4 hist. Watchman or watchmen.  on the watch for waiting for (an anticipated occurrence). Watch it (or oneself) colloq. Be careful. Watch out (often foll. By for) be on one's guard.  watcher n. (also in comb.). [old english: related to *wake1]