IPA: /ˈspuːn.fʊl/
KK: /ˈspuːnˌfʊl/
The quantity of something that can be held in a spoon, often used to measure food or liquid.
She added a spoonful of sugar to her tea.
Spoonful → It is formed from "spoon" (from Old English *spōn*, meaning a utensil for eating or serving) and "-ful" (meaning full of). The word "spoonful" refers to a quantity that fills a spoon.
Think of a spoon that is 'full of' something — that's what a spoonful means.