Practising or tolerant of both homosexual and heterosexual activity; bisexual.
1920s; earliest use found in Aldous Huxley (1894–1963), writer. From omni- + classical Latin futuent-, futuēns, present participle of futuere to have sexual relations with (further etymology uncertain); probably coined (in Latin form omnifutuentes) by Sir Richard Burton 1886 (Terminal Ess §4. D in tr. Arabian Nights X. 238); for usual later spelling in -ant compare -ant.