IPA: /ˈjuːsfəl/
KK: /ˈjusfəl/
Something that is helpful or beneficial in achieving a goal or purpose.
This tool is very useful for fixing things around the house.
Comparative: more useful
Superlative: most useful
Useful → It is formed from "use" (from Old French *user*, meaning to employ or utilize) and "-ful" (meaning full of). The word "useful" means full of use or capable of being employed effectively.
Think of something that is 'full of use' — 'use' means to employ, and '-ful' indicates abundance. This helps you remember that 'useful' describes something that can be effectively employed.