A Watch

1. A portable or wearable timepiece.
2. The act of guarding and observing someone or something.
3. A particular time period when guarding is kept.
4. A period of wakefulness between the two sleeps of a biphasic sleep pattern (the dead sleep or first sleep and morning sleep or second sleep): the first waking.
5. A person or group of people who guard.
6. The post or office of a watchman; also, the place where a watchman is posted, or where a guard is kept.
7. (nautical) A group of sailors and officers aboard a ship or shore station with a common period of duty: starboard watch, port watch.
8. (nautical) 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).
9. The act of seeing, or viewing, for a period of time.