1(forming adjectives from nouns) full of.
- 1.1Having the qualities of.
2Forming adjectives from adjectives or from Latin stems with little change of sense.
3(forming adjectives from verbs) apt to; able to; accustomed to.‘forgetful’
4Forming nouns denoting the amount needed to fill the specified container, holder, etc.‘bucketful’
The combining form -ful is used to form nouns meaning ‘the amount needed to fill’ (cupful, spoonful, etc.). The plural form of such words is cupfuls, spoonfuls, etc. Three cups full would denote the individual cups rather than a quantity measured in cups: on the sill were three cups full of milk; add three cupfuls of milk to the batter