I. -ful¹ /fəl/ suffix [in adjectives]

1. full of something:
an eventful day

2. having the quality of something or causing something:
restful colours
Is it painful?
► -fully /fəli/ suffix [in adverbs]:
shouting cheerfully

[TahlilGaran] Dictionary of Contemporary English ▲

II. -ful² /fʊl/ suffix [in nouns]

1. the amount of a substance needed to fill a particular container:
two cupfuls of milk

2. as much as can be carried by or contained in a particular part of the body:
an armful of flowers

[TahlilGaran] Dictionary of Contemporary English ▲