watch / wäch/ • v. 1. [tr.] look at or observe attentively, typically over a period of time: Lucy watched him go | [intr.] as she watched, two women came into the garden | everyone stopped to watch what was going on. ∎  keep under careful or protective observation: a large set of steel doors, watched over by a single guard. ∎  secretly follow or spy on: he told me my telephones were tapped and I was being watched. ∎  follow closely or maintain an interest in: the girls watched the development of this relationship with incredulity. ∎  exercise care, caution, or restraint about: most women watch their diet during pregnancy | you should watch what you say! ∎  [intr.] (watch for) look out or be on the alert for: in spring and summer, watch for kingfishers watch out for broken glass. ∎  [intr.] [usu. in imper.] (watch out) be careful: credit-card fraud is on the increase, so watch out. ∎  (watch it/yourself) [usu. in imper.] inf. be careful (used as a warning or threat): if anyone finds out, you're dead meat; so watch it.2. [intr.] archaic remain awake for the purpose of religious observance: she watched whole nights in the church.• n. 1. a small timepiece worn typically on a strap on one's wrist.2. [usu. in sing.] an act or instance of carefully observing someone or something over a period of time: the security forces have been keeping a close watch on our activities. ∎  a period of vigil during which a person is stationed to look out for danger or trouble, typically during the night: Murray took the last watch before dawn. ∎  a fixed period of duty on a ship, usually lasting four hours. ∎  (also star·board or port watch) the officers and crew on duty during one such period. ∎ fig. the period someone spends in a particular role or job. ∎  (usu. the watch) hist. a watchman or group of watchmen who patrolled and guarded the streets of a town before the introduction of the police force. ∎  a body of soldiers making up a guard.PHRASES: be on the watch be carefully looking out for something, esp. a possible danger.keep watch stay on the lookout for danger or trouble.watch one's mouthsee mouth.the watches of the night poetic/lit. the hours of night, portrayed as a time when one cannot sleep.watch (one's) penniessee penny.watch one's step used as a warning to someone to walk or act carefully.watch this spacesee space.watch the time ensure that one is aware of the time in order to avoid being late.DERIVATIVES: watch·er n. [often in comb.] a bird-watcher.