wylie·coat \ˈwīliˌkōt, ˈwil-\noun Etymology: Middle English (Scots) wyle cot, from wyle (of unknown origin) + cot, cote coat — more at coat 1.chiefly Scotland: a warm undergarment 2.chiefly Scotland: petticoat 3.chiefly Scotland: a nightgown for a woman or child