horizontal

Universal Words adjective, noun adjective flat and level; going across and parallel to the ground rather than going up and down: horizontal and vertical lines * (informal) I was so tired, I just wanted to be horizontal (= lying down). compareVERTICAL horizontally adverb: Cut the cake in half horizontally and spread jam on one half. noun 1 (the horizontal) [U] a horizontal position: He shifted his position from the horizontal. 2 [C] a horizontal line or surface