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English definition of “speed”

speed

noun [C/U]  /spid/ us  
(a) rate at which something moves or happens: [C] a speed of 25 miles per hour [U] Both cars were traveling at high speed. [U] They came racing down the hill at top speed (= as fast as they could go). [U] The processing speed of my new computer is much faster. [C] This electric drill has two speeds (= rates at which it turns). physics Speed is also the rate at which something travels, expressed as the number of meters in a second. A speed is also a gear (= part that controls the rate at which a vehicle moves): [C] I have a ten-speed bicycle.
speedily
adverb  /ˈspi·dəl·i/ us  
The error can be speedily corrected.

speed

verb [I/T]  /spid/ (past tense and past participle sped  /sped/ or speeded) us  
to move, go, or happen fast, or to cause something to happen fast: [I] The train sped along at over 120 miles per hour. [I] This year seems to be speeding by/past. [T] Ambulances sped the injured people (= moved them quickly) away from the scene.
Phrasal verbs
(Definition of speed from the Cambridge Academic Content Dictionary © Cambridge University Press)
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