What type of morpheme is an example of 'book'?

The term "book" is categorized as a free morpheme because it can stand alone as a complete word with its own meaning. Free morphemes are those that do not require additional morphemes to convey meaning. They can function independently in a sentence, while bound morphemes, in contrast, cannot stand alone and must attach to other morphemes to convey meaning.

For instance, while "un-" is a bound morpheme that requires attachment to another word to form meanings like "untie," "book" is independent and readily understood without any additional modifications. As such, it serves as a fundamental unit of meaning in the English language. This quality distinguishes "book" as a free morpheme, highlighting its role as a base word that can serve as a building block in language, unlike affixes or phonemes which perform different functions within word formation and pronunciation.