coitus vs sex act

coitus and sex act both are nouns.

Word	Noun	Adjective	Verb	Adverb
coitus	Yes	No	No	No
sex act	Yes	No	No	No

As nouns, coitus and sex act are synonyms defined as:

coitus and sex act: sexual activity between individuals, especially the insertion of a man's penis into a woman's vagina until orgasm and ejaculation occur

coitus (noun)	sex act (noun)
sexual activity between individuals, especially the insertion of a man's penis into a woman's vagina until orgasm and ejaculation occur	sexual activity between individuals, especially the insertion of a man's penis into a woman's vagina until orgasm and ejaculation occur