1.
speed; quickness; rapidity
Noun formed from 速い (fast), referring to how fast something moves or happens. Also used for speed as a magnitude in everyday and scientific contexts.
Formed from the i-adjective 速い + さ (a suffix that turns adjectives into nouns expressing degree). Refers to the rate of motion or how quickly something is done.
Common collocations
- 音の速さ: the speed of sound
- 速さを増す: to increase speed
- 目にも留まらぬ速さ: dizzying speed (lit. too fast for the eye to catch)
Similar words
- 速度: speed, velocity — more technical and measured (e.g. km/h); 速さ is the everyday word
- 早さ: earliness — same reading but written 早, about timing (being early) rather than rate of motion
Related Words
Compare:
速度 (speed, velocity)