Which term is defined as the smallest unit of speech sounds in a word?

The term that refers to the smallest unit of speech sounds in a word is a phoneme. Phonemes are the distinct units of sound that can differentiate meaning in a language. For example, in the word "cat," the individual sounds /k/, /æ/, and /t/ are each phonemes. These sounds are crucial for the pronunciation and understanding of words.

Phonemes differ from graphemes, which are the written representation of sounds (letters or combinations of letters), and morphemes, which are the smallest units of meaning in a word (such as prefixes or suffixes). Syllables are units of sound that contain at least one vowel sound and may consist of multiple phonemes. In this way, phonemes serve as the foundational building blocks of spoken language, essential for accurate communication and literacy development.