IPA: /ˈtjuːn.fəl/
KK: /ˈtjunfəl/
Having a pleasant and musical sound; melodious.
The tuneful song filled the air with joy.
Comparative: more tuneful
Superlative: most tuneful
Tuneful → It is formed from "tune" (from Old French *ton*, meaning a musical sound or melody) and "-ful" (meaning full of). The word "tuneful" means full of melody or having a pleasant musical quality.
Think of a 'tune' that is 'full of' pleasant sounds — that's what tuneful means.