noun

Any of the various phonetic realizations of a phoneme in a language, which do not contribute to distinctions of meaning. For example, in English an aspirated p (as in pin) and unaspirated p (as in spin) are allophones of the phoneme /p/, whereas in ancient Greek the distinction was phonemic.

A phone is a realization in sound of a phoneme, and an allophone is one such realization among others: for example, English /n/ is normally alveolar, but is dental before the dental fricative in ‘tenth’.