Definition of: speed

(spēd) noun
1. The act or state of moving or progressing swiftly; rapidity of motion; celerity; swiftness.
2. Physics a Rate of motion, especially as considered without reference to direction: a scalar quantity distinguished from velocity. b Rate of performance, as shown by the ratio of work done to time spent.
3. Mech. A transmission gear in a motor vehicle.
4. Phot. In a camera lens, the minimum time required for an effective exposure under given conditions, expressed as the ratio of focal length to effective aperture.
5. Slang One of the amphetamines taken illicitly, especially by injection.
6. Archaic Good luck; success; prosperity.
—v. sped or speed·ed, speed·ing v.i.
1. To move or go with speed.
2. Obs. To prosper.
3. Obs. To fare in a specified manner.
—v.t.
4. To promote the forward progress of; cause to move or go with speed.
5. To promote the success of.
6. To wish Godspeed to: Speed the parting guest.
—to speed up To accelerate in speed or action. See synonyms under FLY¹.
—adjective Having, pertaining to, characterized by, regulating, or indicating speed: used chiefly in compounds:

[OE spēd power]