Definitions
1.NounA movement ahead or forward.
2.NounForward motion, or its rate.
3.NounThe interval of time or distance between the fronts of two vehicles (e.g. buses) moving in succession in the same direction, especially along the same pre-determined route.
4.NounProgress toward a goal.
5.NounThe clearance beneath an object, such as an arch, ceiling or bridge; headroom.
6.NounA crossheading.