1 : a situation in which events happen at the same time in a way that is not planned or expected [noncount] ▪ It was mere/pure/sheer coincidence that brought them together so far from Chicago. ▪ By coincidence, every man in the room was named Fred. ▪ Our meeting happened by coincidence. [=by chance] [count] ▪ “I'm going to Boston this weekend.” “What a coincidence! I am too.” ▪ It was no coincidence that he quit his job at the bank a day after the robbery. ▪ a series of strange coincidences ▪ By a fortunate/happy coincidence, we arrived at the theater at the same time.2 [singular] formal : the occurrence of two or more things at the same time
▪ Scientists have no explanation for the coincidence of these phenomena.3 [singular] formal : the state of two or more things being the same — often + of ▪ There is a coincidence of interests between the companies. [=the companies share the same interests]
▪ Scientists have no explanation for the coincidence of these phenomena.