IPA: /ˈræpɪdɪst/
KK: /ˈræpɪdɪst/
The highest degree of being fast or quick.
The cheetah is the rapidest animal on land, able to reach incredible speeds.
Comparative: more rapid
Superlative: rapidest
Rapidest → It is formed from "rapid" (from Latin "rapidus", meaning swift or quick) and the superlative suffix "-est" (meaning most). The word "rapidest" means the most swift or quick.
Think of 'rapid' meaning swift, and remember that 'rapidest' refers to the most swift.