Which suffix is an example of a derivational suffix?

A derivational suffix is one that changes the meaning or grammatical category of a word, often creating a new word entirely. The suffix -ness fits this definition because it transforms adjectives into nouns. For example, when added to the adjective "happy," it creates the noun "happiness," indicating a state or quality derived from the original adjective.

In contrast, the other suffixes primarily serve grammatical functions without significantly altering the word's category or introducing new meanings. The suffix -ed typically indicates past tense for verbs, -ing denotes the gerund form or present participle of verbs, and -s generally indicates plurality for nouns. Although these suffixes alter the form of the words they attach to, they do not create new words in the same way that -ness does.