Define the term "morpheme."

The term "morpheme" refers to the smallest unit of meaning in a word, making it a fundamental concept in the study of linguistics and language development. Morphemes can be whole words, such as "cat," or parts of words, such as prefixes and suffixes like "un-" in "undo" or "-ing" in "running." This definition is essential for understanding how words are constructed and how they convey meaning, which is particularly important in reading instruction and literacy development.

In contrast, the other options do not accurately describe what a morpheme is. The smallest unit of sound in a word is known as a phoneme, which is distinct from the concept of morphemes. The main idea of a text refers to the central theme or message rather than a linguistic unit. Lastly, a synonym describes a word that has a similar meaning to another word but is unrelated to the structure of meaning within individual words. Understanding morphemes is crucial for breaking down and analyzing words, which supports literacy and comprehension skills in young readers.