IPA: /ˈsmuːθɪst/
KK: /smuðɪst/
The highest degree of being even and without bumps or roughness.
This is the smoothest surface I have ever touched.
Comparative: smoother
Superlative: smoothest
To make something even or free of bumps; to make a surface flat and pleasant to touch.
She will smooth the fabric before sewing it.
Past: smoothed
Past Participle: smoothed
Smoothest → It is formed from "smooth" (from Old English "smeoth", meaning even or level) and the suffix "-est" (used to form the superlative degree). The word "smoothest" means the most even or level surface or texture.
Think of something being the 'most even' or 'level' — 'smooth' describes a surface without bumps, and '-est' indicates it is the highest degree of smoothness.