What does the term "morpheme" refer to in language?

The term "morpheme" refers specifically to the smallest unit of meaning in a word. Morphemes can be individual root words, prefixes, or suffixes that convey meaning. For example, in the word "unhappiness," there are three morphemes: "un-" (meaning "not"), "happy" (the root meaning), and "-ness" (indicating a state or condition). Together, these morphemes combine to create a complete meaning: the state of not being happy. This understanding of morphemes is crucial in reading and linguistics, as they play a key role in word formation and comprehension, aiding in vocabulary development and language learning.