出典:Wiktionary
The noun is borrowed from southern French picaillon, pécaillon, picayon (“type of small foreign coin; (くだけた用法, especially in the 複数形) cash, money”), and from its etymon Occitan picalhon, picaioun (“cheaply made Savoyan-Piedmontese coin that was rapidly demonetized; (by extension) cash, money”), probably from Occitan piquar (“to ring (bells); to knock, strike”) (referring to the clinking of coins in a pocket), originally imitative.[1]
The adjective is derived from the noun.
picayune (複数形 picayunes) (chiefly US)
picayune (comparative more picayune, superlative most picayune) (chiefly US, informal)