Emily Dickinson Lexicon

FOP, n. [Sp. and Port. guapo, spruce, gay, affected, foppish, affectedly nice; also in Sp. stout, bold, from the root of vapor, vapid; Sp. guapear, to brag. The Latin vappa, a senseless fellow, is evidently from the same root, with the sense of emptiness or lightness.]

A vain man of weak understanding and much ostentation; one whose ambition is to gain admiration by showy dress and pertness; a gay trifling man; a coxcomb.