Das OED online sagt für plait:
“a. A single length of hair, straw, rope, etc., made up of three or more interlaced strands; esp. a tress of interwoven strands of hair, a braid, a pigtail; a flat band of braided vegetable fibre, used to make hats, etc.; (as a mass noun) such bands viewed collectively, as a manufactured product.Sometimes qualified by a number signifying the quantity of strands of which the plait is made up, as four-plait, five-plait, six-plait, etc.; (also) three-a-plait, four-a-plait, etc., a plait of three, four, etc., plaits (Eng. regional (north.))” und gibt u.a. das Beispiel
“2003 Sugar Aug. 88/4 For a French plait, start as you would for a normal plait but pull more hair into the braid with each fold, securing the plait flat against your head.”
Unter ‘braid’ findet man:
a. Anything plaited, interwoven, or entwined; esp. A plait of human hair. In 19th c. sometimes applied to the flat bands of hair, worn at one time by ladies over the side of the face, as in early portraits of Queen Victoria."
Die Grenzen sind also wirklich fließend.