What do free (unbound) morphemes represent in language?

Free morphemes are the smallest units of meaning in a language that can stand alone as independent words. They represent complete ideas or concepts without requiring any additional elements to convey meaning. For instance, words like "book," "run," and "happy" are all free morphemes because they can function independently and are meaningful on their own in communication.

Understanding free morphemes is crucial in linguistics since they serve as the foundation for building more complex words and phrases. They can also be combined with bound morphemes (which cannot stand alone) to create new words, but their essence lies in their ability to exist independently.

The other options do not accurately capture the definition of free morphemes. Some words may carry meaning but not stand alone, and the presence or absence of prefixes or compound structures does not influence whether a morpheme is free or bound. Therefore, recognizing that free morphemes can stand alone is a key aspect of understanding their role in language.