What is the term for the use of the mouth on the penis of a male?

The correct answer is the term "Fellatio." This term specifically refers to the act of oral stimulation of the male genitalia, particularly the penis. It is derived from the Latin word "fellare," which means "to suck." This distinction is important as it highlights the specific nature of the act in contrast to other terms that may encompass broader sexual activities.

Oral sex, while also correct in describing any oral stimulation of the genital areas, is a more general term that applies to both male and female partners. Intercourse typically refers to penetrative sexual activity, usually involving vaginal or anal penetration, while coitus is also focused on penetrative acts and is derived from Latin as well. Therefore, while all these terms relate to sexual activity, "Fellatio" is the precise term for the act in question, emphasizing the specific technique involved.