noun

• (obsolete) A plot, a scheme.
  "Besides some care is taken, so far as conveniently can be, both to give regard to the further spring of any matter tending to the entry or execution of any other or evil plat, and also upon the sight thereof, to have timely recourse to the King, to warn him and others to beware and provide for the seasonable prevention of the danger; [...]"

verb

• (transitive) To create a plat; to lay out property lots and streets; to map.
  "A husband can not, without authority from his wife, plat her land, and the fact that the land which he assumes to plat was omitted by mistake from a previous plat made and acknowledged by her can make no difference."

verb

• (dated except regional England) To braid, to plait.
  "And when they had platted a crowne of thornes, they put it upon his head, and a reed in his right hand: and they bowed the knee before him, and mocked him, ſaying, haile king of the Jewes."

adj

• (obsolete except Scotland) Flat; level; (by extension) frank, on the level.
  "But else, hold alway^([sic]) your tail fast between your legs that he catch you not thereby; and hold down your ears lying plat after your head that he hold you not thereby; and see wisely to yourself."