A suffix is a morpheme or words added at the end of the word to form a new word or change the meaning of the word.
Hence, suffixes which can be added to a word to form an adjective are, -able, -ful, -ish, -less, -ly and so forth.
Adjectives formed while adding the above suffixes in a word will be
Flexible (verb- flex which means to bend),
Helpful (verb- help which means to support),
Childish (noun- child),
Hopeless (verb- hope that means to wish), and
Monthly (noun- month).