o·ver·turn • v. / ˌōvərˈtərn/ [tr.] 1. tip (something) over so that it is on its side or upside down: the crowd proceeded to overturn cars and set them on fire. ∎  [intr.] turn over and come to rest upside down, typically as the result of an accident: a large housetrailer overturned in the middle of the road.2. abolish, invalidate, or turn around (an established fact, system, etc.): the results overturned previous findings. ∎  reverse (a legal decision): he fought for eight years to overturn a conviction for armed robbery.• n. / ˈōvərˌtərn/ rare an act of turning over or upsetting something; a revolution, subversion, or reversal. ∎  Ecol. the occasional (typically twice yearly) mixing of the water of a thermally stratified lake.

overturn See thermal stratification.