1602. Dekker, Honest Whore. Old Plays, iii., 304. Come, Sirrah, you flat-cap, where be those whites?
1605. Marston, Dutch Court, ii., 1. Wealthy flat-caps that pay for their pleasure the best of any men in Europe.
1613. Beaumont and Fletcher, Hon. Man’s Fort., v. 3. Trade? to the city, child: a flat-cap will become thee.
Flat-cock, subs. (old).—A female. [Grose, 1785.] For synonyms, see Petticoat.
Flat-feet, subs. (common).—Specifically the Foot Guards, but also applied to other regiments of the line. Also (generally with some powerful adjective), applied to militia men to differentiate them from linesmen. For synonyms, see Mud-crusher.
Flat-fish, (generally, a regular flat-fish) subs. (common).—A dullard. [A play upon flat = stupid, and Fish = something to hook or catch.] For synonyms, see Buffle, Cabbage-Head, and Sammy-Soft. Cf., Fr., platpied = a contemptible fellow.
Flat-footed, adj. (American).—Downright; resolute; honest. [Western: the simile, common to most languages, is of a man standing, his back to the wall, resolute to accomplish his purpose.]
1858. Harper’s Magazine, Sept. His herculean frame, and bold, flat-footed way of saying things, had impressed his neighbours, and he held the rod in terrorism over them.
1871. Philadelphia Bulletin, Mar. 23. ‘The row at St. Clement’s Church.’ Now the Committee of the vestry put their foot flatly down on auricular confession and priestly absolution.
1887. R. A. Proctor, Knowledge, June 1. When, in America, General Grant said he had put his foot down and meant to advance in that line if it took him all the summer, he conveyed … the American meaning of the expression flat-footed.