c.1440, "to set up, fix," from up + set (v.). Cf. M.Du. opsetten, Ger. aufsetzen. Modern sense of "overturn, capsize" (1803) is that of obsolete overset. Meaning "to throw into mental discomposure" is from 1805. The noun sense of "overturning of a vehicle or boat" is recorded from 1804.