<p><strong>Verb</strong></p><ul><li>(used without object) to be alertly on the lookout, look attentively, or observe, as to see what comes, is done, or happens: to watch while an experiment is performed.</li><li>to look or wait attentively and expectantly (usually followed by for): to watch for a signal; to watch for an opportunity.</li><li>to be careful or cautious: Watch when you cross the street.</li><li>to keep awake, especially for a purpose; remain vigilant, as for protection or safekeeping: to watch with a sick person.</li><li>to keep vigil, as for devotional purposes.</li><li>to keep guard: She was assigned to watch at the door.</li></ul><p><strong>Noun</strong></p><ul><li>close, continuous observation for the purpose of seeing or discovering something: Their watch for the birds was unrewarding.</li><li>vigilant guard, as for protection or restraint: to keep watch for prowlers.</li><li>a keeping awake for some special purpose: a watch beside a sickbed.</li><li>a period of time for watching or keeping guard: to stand the first watch.</li><li>a small, portable timepiece, as a wrist watch or pocket watch.</li><li>a chronometer.</li><li>Nautical. a period of time, usually four hours, during which one part of a ship's crew is on duty, taking turns with another part.</li><li>the officers and crew who attend to the working of a ship for an allotted period of time.</li><li>one of the periods, usually three or four, into which the night was divided in ancient times, as by the Greeks or Hebrews: the fourth watch of the night.</li><li>a person or group that watches, as a lookout, guard, or sentinel: A watch was posted at sunset.</li><li>also called storm watch. Meteorology. an announcement from the U.S. National Weather Service alerting the public that dangerous weather conditions are a possibility and that vigilance and precautionary preparations are advised: tornado watch.</li><li>a flock of nightingales.</li></ul><p><strong>Verb Phrase</strong></p><ul><li>to be on one's guard; be cautious: Watch out for cars when you cross the road.</li><li>to guard for protection or safekeeping: She watched over us like a mother hen over her brood.</li></ul>