What type of affix alters the meaning of a base word to derive a new word?

A derivational affix is a type of affix that modifies the meaning of a base word and creates a new word by changing its form or part of speech. For instance, when the prefix "un-" is added to the word "happy," it transforms the meaning to "not happy," thus forming the new word "unhappy." Similarly, the suffix "-ness" can be added to "happy" to create "happiness," indicating a different grammatical category (from adjective to noun) and a shift in meaning.

This process of word formation through derivational affixes is essential in expanding vocabulary and allowing for the expression of new ideas. It enables language flexibility, providing speakers and writers with the tools to convey more nuanced meanings. In contrast, inflectional affixes modify a word’s tense, number, or case without creating a new word; bound morphemes cannot stand alone and cannot form words by themselves; and phrase affix is not a recognized linguistic category. Therefore, derivational affixes are crucial for understanding how new words are formed in English language structure.