What term describes the smallest unit in a language that carries meaning?

The term that describes the smallest unit in a language that carries meaning is a morpheme. Morphemes can be either a whole word or a part of a word, such as a prefix or suffix. For example, the word "unhappiness" consists of three morphemes: "un-" (a prefix meaning 'not'), "happy" (the root), and "-ness" (a suffix indicating a state or condition). Each of these components contributes to the overall meaning of the word, demonstrating how morphemes function as the basic building blocks of meaning in language.

In contrast, graphemes refer to the smallest units of written language, such as letters or characters, and phonemes are the smallest units of sound in speech that distinguish one word from another but do not convey meaning on their own. The term "digit" typically relates to numerical symbols or figures, which is not relevant in the context of linguistic units. Thus, morphemes are the correct choice when considering components that specifically convey meaning within a language.