Adding -ful or -fully

The suffix -ful can form nouns or adjectives, like plateful or cheerful. People sometimes make the mistake of spelling this type of word with a double l at the end. Note that it is always spelled with just one -l:

dreadful, faithful, skillful, powerful

cupful, mouthful, spoonfuls

The related ending –fully forms adverbs. Remember that this suffix is always spelled with two l’s:

dreadfully, faithfully, skillfully, powerfully

Grammar and usage