co·in·ci·dent / kōˈinsədənt; -ˌdent/ • adj. occurring together in space or time: liberty is an idea coincident with the spread of Christianity. ∎  in agreement or harmony: the stake of defense attorneys is not always coincident with that of their clients.DERIVATIVES: co·in·ci·dent·ly / kōˌinsəˈdentlē/ adv.

co·in·ci·den·tal / kōˌinsəˈdentl/ • adj. 1. resulting from a coincidence; done or happening by chance.2. happening or existing at the same time: it's convenient that his plan is coincidental with the group's closure.DERIVATIVES: co·in·ci·den·tal·ly / kōˌinsəˈdentlē; -ˈdentl-ē/ adv.