What characteristic do multi-syllabic words usually have?

Multi-syllabic words typically possess at least one prefix or suffix, which contributes to their length and complexity. Prefixes are added to the beginning of a root word to modify its meaning, while suffixes are added to the end of a root word. Together, they help to create words that convey more detailed or nuanced meanings than their base forms. For example, the word "unhappiness" has both a prefix ("un-") and a suffix ("-ness"), indicating a state of being not happy.

The other options do not accurately reflect the nature of multi-syllabic words. Words without prefixes or suffixes would generally be simpler and often consist of fewer syllables. Multi-syllabic words can be nouns, verbs, adjectives, or adverbs; therefore, they are not limited to just being nouns. Finally, the reference to simple sentences is unrelated to the characteristics of words and their syllable count. Thus, the correct characteristic is that multi-syllabic words have at least one prefix or suffix.