duff [E18th] There are a bewildering number of different word histories for duff. The oldest is a term for small coal particles, which is probably a variant of the flour and water mixture dough [OE], and is also behind the sweet plum duff [E19th], where duff is simply a northern variant of dough. Another duff [L18th] is a term for something counterfeit, particularly money, which gives us the adjective duff [L19th] for something inadequate, or poorly done, although there is another verb to duff [L19th] used by golfers for ‘to perform a shot badly’ and extended to make a mess of something which is probably an influence. To duff someone up [M20th], or beat them up, is probably an imitation of the noise of a blow, a sense of duff found from the mid 19th century. Up the duff [M20th] for pregnant started out as Australian slang and may be a play on other terms for pregnant such as a bun in the oven and in the pudding club. Which of these lies behind duffer [M19th] for someone who is inadequate in a job or generally stupid is not clear; suggestions include an earlier duffer [M18th] for a dishonest pedlar, or in Australia someone who fakes cattle brands, or an early 18th-century Scottish word for a fool, a dowfart.