Some Greek speaking acquaintances have suggested to me that this word is related to the Greek word μοίρα, which means “fate”. Although there is a romantic streak in me that rather likes the idea, sadly I have to admit that this is not the case.
“Marriage” has an altogether different story to tell. It made its debut sometime towards the end of the 13th century, where it is in the Middle English form mariage. This derives from Old French mariage. The French term came from Vulgar Latin maritaticum, which was itself from Latin maritatus. This was the past participle of the verb “to marry, to wed”, also meaning “to give in marriage”. This verb was maritare.
The road from here further into the past is uncertain. However, one theory is that it comes from a Proto-Indo-European root *meri, meaning “young woman” or perhaps “young wife”. If this is the case, it would make it a cognate of the Welsh merch, which means “girl”.
It’s worth noting that although the meaning today is related to “marriage”, the word “wed” originally meant “pledge, promise”, and was first used in the sense of marry with the meaning “give a pledge to take a woman”, and it referred to the man’s action. Other languages have retained the “pledge” meaning, and its root is the source of German Wette, which means “bet, wager”.