watch

(noun): A portable or wearable timepiece.
(noun): The act of guarding and observing someone or something.
(noun): A particular time period when guarding is kept.
(noun): A person or group of people who guard.
(noun): The post or office of a watchman; also, the place where a watchman is posted, or where a guard is kept.
(noun): A group of sailors and officers aboard a ship or shore station with a common period of duty: starboard watch, port watch.
(noun): A period of time on duty, usually four hours in length; the officers and crew who tend the working of a vessel during the same watch. (FM 55–501).
(noun): The act of seeing, or viewing, for a period of time.