overturn

verb

• 1tip (something) over so that it is on its side or upside down:the crowd proceeded to overturn cars and set them on fire
• [no object] turn over and come to rest upside down:a coach hit a car and overturned

• 2abolish, invalidate, or reverse (a previous system, decision, situation, etc.):the results overturned previous findings he fought for eight years to overturn a conviction for armed robbery

noun

• an act of overturning something.
• [mass noun] Ecology the occasional (typically twice yearly) mixing of the water of a thermally stratified lake.