Pronunciation: (kō"in-sīd'),[key] —v.i.,-cid•ed, -cid•ing. 1. to occupy the same place in space, the same point or period in time, or the same relative position: The centers of concentric circles coincide. Our vacations coincided this year. 2. to correspond exactly, as in nature, character, etc.: His vocation coincides with his avocation. 3. to agree or concur, as in thought or opinion: Their opinions always coincide.