Which of the following is defined as the smallest unit of speech that distinguishes one word from another?

The term defining the smallest unit of speech that distinguishes one word from another is "phoneme." Phonemes are the individual sounds in a language that, when altered, can change the meaning of a word. For example, in English, the words "bat" and "pat" differ only by the initial phoneme, /b/ and /p/, respectively. This distinction is crucial in understanding language and phonetics, as phonemes serve as the building blocks for words.

Syllables refer to larger units of sound, typically consisting of one vowel sound and may include surrounding consonants. While graphemes relate to the written representation of sounds, they are more connected to the letters and spelling of words rather than the auditory aspect of speech. Phonics is a method of teaching reading and spelling that focuses on the relationship between sounds and their corresponding letters or letter combinations. This all emphasizes the unique role of phonemes in distinguishing meaning in language.