1. a break or opening, as in a fence, wall, or the like; breach.
2. a vacant space or interval.
3. a wide divergence.
4. a deep, sloping ravine or cleft cutting a mountain ridge.
5. Aeronautics the distance between the wings of a biplane.
6. Colloquial a divergence, contradiction, disparity, or imbalance: credibility gap, generation gap, missile gap.
-- verb (t) ( gapped, gapping )
7. to make a gap, opening, or breach in.
[ME, from Scandinavian; cf. Swed. gap opening, chasm, gapa GAPE ]
-- gapless, adjective