a man who is preoccupied with and often vain about his clothes and manners; a dandy

This word might get a lot of attention in England, but it’s certainly underused in the good ol’ US of A. I bumped into it in The Dream of Scipio by Iain Pears: “Now here was Sidonius, brave, foppish, foolish Sidonius, who had decided to take a stand where emperors had failed.”