A complex word is a word that is made up of two or more meaningful parts called morphemes. These morphemes can be prefixes, suffixes, or roots. Each morpheme contributes to the overall meaning of the complex word. For example, the word "unhappiness" is a complex word made up of the prefix "un-", which means "not," and the root "happiness." Together, they create a new word with the meaning of "not being happy." Complex words are an important aspect of language, as they allow us to express more specific meanings and convey more nuanced ideas. Understanding the structure and meaning of complex words can help improve your vocabulary and comprehension skills.