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!). 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. speeder n.
[ OE sped, spedan f. Gmc ]