Which type of affix creates new meaning and often changes the function of a word?

Derivational affixes are crucial in word formation because they create new words and often change the grammatical category or meaning of the base word. For instance, by adding a derivational prefix such as "un-" to the adjective "happy," the new word "unhappy" emerges as a change in meaning that shifts the word from a positive to a negative connotation. Similarly, adding the suffix "-ness" to "happy" forms "happiness," which transforms an adjective into a noun, demonstrating that derivational affixes can alter both the meaning and function of a word.

In contrast, inflectional affixes primarily serve to modify a word's tense, number, mood, or aspect without creating a new meaning or grammatical category. Descriptive and compound forms do not focus on creating new words or shifting grammatical functions in the same way, making derivational affixes unique in their power to expand language and communicate new concepts.