speed speed /ˈspiːd/

noun

1. () Distance travelled per unit time  ( velocity , speed )
   distance travelled per unit time
     The cheetah can reach incredible speeds when chasing its prey.
   The cheetah can reach incredible speeds when chasing its prey.
   
2. () A rate (usually rapid) at which something happens  ( fastness , swiftness , speed )
   a rate (usually rapid) at which something happens
    The project advanced with gratifying speed
   the project advanced with gratifying speed
   
3. () Changing location rapidly  ( hurrying , speeding , speed )
   changing location rapidly
     The athlete sprinted at an incredible speed, breaking the world record.
   The athlete sprinted at an incredible speed, breaking the world record.
   
4. [Informal] A central nervous system stimulant that increases energy and decreases appetite; used to treat narcolepsy and some forms of depression  ( amphetamine , pep pill [Informal] , speed [Informal] , upper [Informal] )
   a central nervous system stimulant that increases energy and decreases appetite; used to treat narcolepsy and some forms of depression
   
5. The ratio of the focal length to the diameter of a (camera) lens system  ( f number , focal ratio , speed , stop number )
   the ratio of the focal length to the diameter of a (camera) lens system
   
   

verb

1. () Move hurridly  ( belt along , bucket along , cannonball along , hasten , hie , hotfoot , pelt along , rush along , step on it , race , rush , speed )
   move hurridly
    He rushed down the hall to receive his guests
   He rushed down the hall to receive his guests
    The cars raced down the street
   The cars raced down the street
   
2. () Move faster  ( quicken , speed up , speed , accelerate )
   move faster
    The car accelerated
   The car accelerated
   
3. () Move very fast  ( travel rapidly , zip , speed , hurry )
   move very fast
    The runner zipped past us at breakneck speed
   The runner zipped past us at breakneck speed
   
4. () Travel at an excessive or illegal velocity  ( speed )
   travel at an excessive or illegal velocity
    I got a ticket for speeding
   I got a ticket for speeding
   
5. () Cause to move faster  ( speed up , accelerate , speed )
   cause to move faster
    He accelerated the car
   He accelerated the car