Inflection/Derivation

[IlmatawTam]

Hello, can somebody explain to me the difference between inflectional and derivational suffixes? If derivational suffixes create a new word belonging to a different part of speech, how come "firmly" is inflectional?

Thank you in advance.

[Soup]

Hello, can somebody explain to me the difference between inflectional and derivational suffixes? If derivational suffixes create a new word belonging to a different part of speech, how come "firmly" is inflectional?

Thank you in advance.

Derivation changes a word's category, whereas inflection does not:


Inflection
[1] Add the suffix -s to the singular noun dog and it become a plural noun dogs. There is no change in category. They are both nouns.


Derivation
[2] Add the suffix -ly to the adjective firm and it becomes the adverb firmly. There is a change in category: an adjective becomes an adverb. This is derivation.


In short, derivation changes a word's category; inflection, on the other hands, does not alter a word's grammatical category.