watch·er /ˈwɑʧɚ/
  看守人,守望者,照顧者
  Watch·er n. One who watches; one who sits up or continues; a diligent observer; specifically, one who attends upon the sick during the night.
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  watcher
       n 1: a close observer; someone who looks at something (such as an
            exhibition of some kind); "the spectators applauded the
            performance"; "television viewers"; "sky watchers
            discovered a new star" [syn: spectator, witness, viewer,
             looker]
       2: a guard who keeps watch [syn: watchman, security guard]
       3: a person who keeps a devotional vigil by a sick bed or by a
          dead body