IPA: /ˈfæt.ləs/
KK: /ˈfæt.ləs/
Having no fat; free from fat content.
The chef prepared a fatless dish that was still very flavorful.
Fatless → It is formed from "fat" (from Old English "fǣtt", meaning the greasy substance in animals) and "-less" (meaning without). The word "fatless" means without fat or lacking fat.
Think of being 'without' ('-less') the 'greasy substance' ('fat') — that's why fatless means lacking fat.