n. - An opening in anything made by breaking or parting; as, a gap in a fence; an opening for a passage or entrance; an opening which implies a breach or defect; a vacant space or time; a hiatus; a mountain pass.
v. t. - To notch, as a sword or knife.
v. t. - To make an opening in; to breach.
n. - The vertical distance between two superposed surfaces, esp. in a biplane.