speed

n. & v.
—n.
1 rapidity of movement (with all speed; at full speed).
2 a rate of progress or motion over a distance in time (attains a high speed).
3 a a gear appropriate to a range of speeds of a bicycle. b US or archaic such a gear in a motor vehicle.
4 Photog. a the sensitivity of film to light. b the light-gathering power of a lens. c the duration of an exposure.
5 sl. an amphetamine drug, esp. methamphetamine.
6 archaic success, prosperity (send me good speed).
—v. (past and past part. sped)
1 intr. go fast (sped down the street).
2 (past and past part. speeded) a intr. (of a motorist etc.) travel at an illegal or dangerous speed. b tr. regulate the speed of (an engine etc.). c tr. cause (an engine etc.) to go at a fixed speed.
3 tr. send fast or on its way (speed an arrow from the bow).
4 intr. & tr. archaic be or make prosperous or successful (how have you sped?; God speed you!).
Phrases and idioms:
at speed moving quickly. speed bump (or hump) a transverse ridge in the road to control the speed of vehicles. speed limit the maximum speed at which a road vehicle may legally be driven in a particular area etc. speed merchant colloq. a motorist who enjoys driving fast. speed up move or work at greater speed. speed-up n. an increase in the speed or rate of working.
Derivatives:
speeder n.
Etymology: OE sped, spedan f. Gmc