sexual relation vs coitus

sexual relation and coitus both are nouns.

Word	Noun	Adjective	Verb	Adverb
sexual relation	Yes	No	No	No
coitus	Yes	No	No	No

As nouns, sexual relation and coitus are synonyms defined as:

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

sexual relation (noun)	coitus (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