Merriam-Webster Collegiate Dictionary - watch

 I. verb  Etymology: Middle English wacchen, from Old English w?ccan — more at wake  Date: before 12th century  intransitive verb  1.  a. to keep vigil as a devotional exercise  b. to be awake during the night  2.  a. to be attentive or vigilant  b. to keep guard  3.  a. to keep someone or something under close observation  b. to observe as a spectator the country ~ed as stocks fell sharply  4. to be expectant ; wait ~ for the signal  transitive verb  1. to keep under guard  2.  a. to observe closely in order to check on action or change being ~ed by the police  b. to look at ; observe sat and ~ed the crowd  c. to look on at ~ television ~ a ball game  3.  a. to take care of ; tend  b. to be careful of ~es his diet  4. to be on the alert for ; bide ~ed her opportunity  II. noun  Date: before 12th century  1.  a. the act of keeping awake to guard, protect, or attend  b. obsolete the state of being wakeful  c. a wake over a dead body  d. a state of alert and continuous attention  e. close observation ; surveillance  f. a notice or bulletin that alerts the public to the possibility of severe weather conditions occurring in the near future a winter storm ~  2.  a. any of the definite divisions of the night made by ancient peoples  b. one of the indeterminate intervals marking the passage of night — usually used in plural the silent ~es of the night  3.  a. lookout, ~man  b. archaic the office or function of a sentinel or guard  4.  a. a body of soldiers or sentinels making up a guard  b. a ~man or body of ~men formerly assigned to patrol the streets of a town at night, announce the hours, and act as police  5.  a.  (1) a portion of time during which a part of a ship's company is on duty  (2) the part of a ship's company required to be on duty during a particular ~  (3) a sailor's assigned duty period  b. a period of duty ; shift  c. a term as holder especially of an overseeing or managerial office the business grew on her ~  6. a portable timepiece designed to be worn (as on the wrist) or carried in the pocket — compare clock