I. ˌō-vər-ˈtərn
Date: 13th century
transitive verb
1. : to cause to turn over : upset
overturn ed the vase
2.
a. : invalidate , destroy
b. : reverse 2a
overturn a court ruling
intransitive verb
: upset , turn over
II. ˈō-vər-ˌtərn noun
Date: circa 1592
1. : the act of overturning : the state of being overturned
2. : the sinking of surface water and rise of bottom water in a lake or sea that results from changes in temperature that commonly occur in spring and fall