1690s, "to write over other writing," from over- + write (v.). Of computers, it is attested from 1959. Meaning "to write too elaborately or ornately" is from 1923. Related: Overwriting; overwritten.
overwrite that file
overwhelm
overwhelmed
overwind
overwinter
overwork
overwrite
overwrought
overzealous
ovi-
Ovid
oviduct