Here's a breakdown of its etymology:
* Latin: "consobrinus" originally meant "son of a mother's sister". It was a legal term referring to a specific type of relative.
* Old French: The word evolved into "cosin" in Old French.
* Middle English: By the Middle English period, the word became "cosyn" and its meaning expanded to include all types of cousins.
* Modern English: Finally, the spelling standardized to "cousin" in Modern English.
So, while originally referring to a specific type of cousin, the word "cousin" has broadened its meaning to encompass all relatives of the same generation as oneself, but not direct descendants.