Is it ensure, insure, or assure?
1620s, "to cast as seed," from Latin inseminatus, past participle of inseminare "to sow, implant," from in- "in" (see in- (2)) + semen (genitive semenis) "seed." Meaning "to impregnate with semen" is attested from 1923. Related: Inseminated; inseminating.
inseminate in·sem·i·nate (ĭn-sěm'ə-nāt')
v. in·sem·i·nat·ed, in·sem·i·nat·ing, in·sem·i·nates
To introduce or inject semen into the reproductive tract of a female.