IPA: /ˈstrɛtʃiɪst/
KK: /ˈstrɛtʃiɪst/
The most able to stretch or be stretched without breaking.
This fabric is the stretchiest material I have ever used for my workout clothes.
Comparative: stretchier
Superlative: stretchiest
Stretchiest → It is formed from "stretch" (from Old English *streccan*, meaning to extend or draw out) and the superlative suffix "-iest" (meaning most). The word "stretchiest" means the most capable of being extended or drawn out.
Think of something that can be extended or drawn out the most — that's what 'stretchiest' means.