Movement ahead or forward.
The 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.
Forward motion, or its rate.
A cross-heading.
The clearance beneath an object, such as an arch, ceiling or bridge; headroom.
Progress toward a goal.
Any outward movement.
Something that flows out of a sewage treatment plant.
The process of flowing out.
A fluid that flows out.
A stream of gaseous material emanating from an active galactic nucleus.
The part of a system that allows material to flow out.
To flow outward.