E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
A fop, a man dressed in fine clothes. A corruption of Tercel-gentle by a double blunder: (1) Tercel, erroneously supposed to be tassel, and to refer to the tags and tassels worn by men on their dress; and (2) gentle corrupted into gentlemen, according to the Irish exposition of the verse, The gentle shall inherit the earth.