Derivational morphology often involves the addition of a derivational suffix or other affix. Such an affix usually applies to words of one lexical category (part of speech) and changes them into words of another such category. For example, one effect of the English derivational suffix -ly is to change an adjective into an adverb (slow → slowly).

Here are examples of English derivational patterns and their suffixes:

• adjective-to-noun: -ness (slow → slowness)
• adjective-to-verb: -en (weak → weaken)
• adjective-to-adjective: -ish (red → reddish)
• adjective-to-adverb: -ly (personal → personally)
• noun-to-adjective: -al (recreation → recreational)
• noun-to-verb: -fy (glory → glorify)
• verb-to-adjective: -able (drink → drinkable)
• verb-to-noun (abstract): -ance (deliver → deliverance)
• verb-to-noun (agent): -er (write → writer)

Derivation can be contrasted with inflection, in that derivation produces a new word (a distinct lexeme), whereas inflection produces grammatical variants (or forms) of the same word.

• A non-exhaustive list of derivational morphemes in English: -ful, -able, im-, un-, -ing, -er
• A non-exhaustive list of inflectional morphemes in English: -er, -est, -ing, -en, -ed, -s