More people today carry a watch on their wrists than in their pockets; some people today don't use a watch at all, because their smartphone serves the purpose well enough.
noun The act of guarding and observing someone or something.
noun A particular time period when guarding is kept.
The second watch of the night began at midnight.
noun 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.
noun A person or group of people who guard.
The watch stopped the travelers at the city gates.
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).