Definition - The smallest unit of identifiable speech sound that can be transcribed with an IPA symbol — i.e. the smallest part of speech that listener's recognize as a complete vowel or consonant.

1. In contrast, phonemes are the smallest units of meaningful sound.
2. By convention, phones are bracketed ( [b]), whereas phonemes are displayed between slashes ( /b/).

Example -
In the words lap and lab the /p/ and /b/ are phonemes. However, in the words lap and plug, though the two p's represent different sounds and are, thus, represented by two different phones, they both are still represented by the same phoneme.

Etymology -
The word derives from the Greek phone, sound or voice.

Oxford English Dictionary -
Its first citation is from 1866:
"When I mean words as sounded I shall use the term phone…."
(J. Grote in Jrnl. Philol. (1872) IV. 55 )

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