To perform oral sex on someone, specifically stimulation of the penis with the mouth.
From Latin fellare, meaning 'to suck,' which may derive from PIE roots related to sucking or drawing in. The verb form emerged in English medical/sexological texts in the late 19th century.
Fellate is one of the few English words that comes directly from a Latin root referring to sexual behavior—most sexual vocabulary came through Germanic roots or became Latin-ized over time for clinical distance.
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