1. The rate of movement; distance travelled per unit time
   "The car reached a speed of 60 miles per hour";
   - velocity
    
2. A rate (usually rapid) at which something happens
   "the project advanced with gratifying speed";
   - swiftness, fastness
    
3. The act of moving or travelling faster than usual
   "Their speed had not helped, the train had already left";
   - speeding, hurrying
    
4. The ratio of the focal length to the diameter of a (camera) lens system
   "The lens had a maximum speed of f/1.8";
   - focal ratio, f number, stop number
    
5. [informal] A central nervous system stimulant that increases energy and decreases appetite; used to treat narcolepsy and some forms of depression
   "The student illegally used speed to stay awake during exam week";
   - amphetamine, pep pill [informal], upper [informal]

1. Move or travel very quickly
   "He sped down the hall to receive his guests";
   - rush, hotfoot, hasten, hie [archaic], race, pelt along [informal], rush along, bucket along [informal], belt along [informal], step on it [informal], travel rapidly, hurry, zip [informal], zoom, zoom along [informal], whizz [informal], whizz along [informal], bucket [informal], belt [informal], barrel [informal], rocket [informal], wing [informal], pelt [informal]
    
2. Move faster
   "The car sped up";
   - accelerate, speed up, quicken
    
3. Travel at an excessive or illegal velocity
   "I got a ticket for speeding"
    
4. Cause to move faster
   "He sped up the car";
   - accelerate, speed up

Derived forms: speeded, speeding, sped, speeds

See also: fast, slow

Type of: alter, change, deepen, drug of abuse, excitant, go, intensify, locomote, modify, motion, move, movement, pace, rate, ratio, stimulant, stimulant drug, street drug, travel

Encyclopedia: Speed, North Carolina