coitus

The word 'coitus' is a direct borrowing from Latin, where 'coitus' means "a coming together, meeting, or uniting." It is the past participle of the verb 'coire,' which is itself a compound of 'co-' (a variant of 'com-,' meaning "together") and 'ire' (meaning "to go"). Thus, the literal sense is "a going together." This Latin term was adopted into English in the 18th century as a technical and formal term for sexual union, carrying the abstracted meaning of a physical joining from its original, more general sense of meeting or conjunction.

The word is a simplex loanword from Latin. It cannot be meaningfully segmented into smaller, independent morphemes using its current English spelling.