fustian

The noun is derived from Middle English fustian (“type of fabric, probably made from cotton, flax, or wool; piece of fustian spread over a bed or mattress”) [and other forms], from Old French fustaine, fustaigne (modern French futaine), from Medieval Latin fūstāneum, from (pannus) fūstāneus or (tela) fūstānea, of disputed origin.

Sense 3 (“inflated, pompous, or pretentious speech or writing”) is possibly from the fact that the fabric was sometimes used to make cushion- and pillowcases, thus suggesting that the speech or writing is “padded” or “stuffed”; compare bombast. The relationship between sense 4 (“hot drink made of a mixture of alcoholic beverages with egg yolk, lemon, and spices”) and the fabric is unclear.

The adjective is from an attributive use of the noun.