IPA: //ˈsmuːðər//
KK: /smuðɚ/
Having a surface that is even and free from bumps or roughness; more even than something else.
The new road is much smoother than the old one.
Comparative: smoother
Superlative: smoothest
A tool or device that makes a surface flat or even by removing bumps or irregularities.
The carpenter used a smoother to finish the wooden table.
Smoother → It is formed from "smooth" (from Old English *smeðe*, meaning even or level) and "-er" (meaning one who or that which). The word "smoother" refers to something that makes a surface more even or level.
Think of something that makes a surface 'even' or 'level' — that's what smoother means.