はやい
fast, quick
そくど
speed
こうそく
high speed
きゅうそく
rapid (e.g., progress)
かそく
acceleration
かそくど
さっそく
at once, immediately, promptly
じそく
speed (per hour)
そくたつ
express, special delivery
そくりょく
じんそく
quick, fast, prompt