Word Origin & History
1670s, the kind of coarse, abusive language once used by women in the Billingsgate market (mid-13c., not exclusively a fish market until late 17c.) on the River Thames below London Bridge.
"Billingsgate is the market where the fishwomen assemble to purchase fish; and where, in their dealings and disputes they are somewhat apt to leave decency and good manners a little on the left hand." ["Dictionary of the Vulgar Tongue," 1811]
The place name is O.E. Billingesgate, "gate of (a man called) Billing;" the "gate" probably being a gap in the Roman river wall.