what is origin of o'clock
Word History: The origin of o'clock is no mystery: it is a contraction of of the clock, a codification, in fact, of a spelling error. It is not alone in this category: we also find jack-o'-lantern, will-o'-the-wisp, and no doubt others there. Clock itself has an interesting history. It originally meant bell and was derived from a verb meaning to strike, Old English cluccgan. It probably originally referred to a bell clapper.