Here are some possible terms that may be close to what you are looking for and their characteristics:
* Phoneme: This is a fundamental unit of sound in a language that distinguishes one word from another. For example, the phonemes /p/ and /b/ distinguish the words "pat" and "bat." Characteristics of phonemes include:
* Distinctive: They change the meaning of a word.
* Minimal pairs: Words that differ only by a single phoneme.
* Allophones: Variations of a phoneme that don't change the meaning of a word (e.g., the aspirated /p/ in "pin" and the unaspirated /p/ in "spin").
* Morpheme: This is the smallest meaningful unit in a language. It can be a word (e.g., "cat") or a part of a word (e.g., the "-ing" in "running"). Characteristics of morphemes include:
* Meaningful: They carry a specific meaning.
* Free morphemes: Can stand alone as a word.
* Bound morphemes: Must be attached to other morphemes.
* Phonetics: This is the study of speech sounds, their production, and perception. It examines how sounds are produced by the vocal tract and how they are heard and understood.
If you can provide more context or information about what you were looking for, I can help you find the appropriate term and explain its characteristics.