Clock：An instrument for the measurement of time; properly, one in which the hours, and sometimes lesser divisions, are sounded by strokes of a hammer on a bell or similar resonant body; but many clocks now do not strike. The mechanism consists of a train of wheels set in motion by weights or a spring, actuating and regulated by a pendulum or balance-wheel, and requiring to be periodically wound up; the passage of hours, minutes, etc., is indicated by ‘hands’ or pointers, on a ‘face’ or dial-plate.---Oxford English Dictionary   Clock：an instrument that shows what time it is, in a room or outside on a building---Longman Dictionary of Contemporary English  @en