overflow verb [ I/T ] us / ˌoʊ·vərˈfloʊ / Add to word list (of a liquid) to flow over the edges of a container because there is too much, or to contain more of something than can be held: [ T ] Because of the heavy rains, the river overflowed its banks. [ I ] The sink quickly overflowed, flooding the room.

overflow verb (CONTENTS) to come out of a container or a place because it is too full: The river overflowed its banks after the heavy rainfall.

verb (used without object), o·ver·flowed, o·ver·flown, o·ver·flow·ing. to flow or run over, as rivers or water: After the thaw, the river overflows and causes great damage. to have the contents flowing over or spilling, as an overfull container: Stop pouring or your glass is going to overflow.