Found:
phoneme
PHONOLOGY: structuralist concept of the smallest unit by which one can 
distinguish one word from another (e.g. Jacobson, Trubetzkoy). The phonemes of 
a language can be found by constructing minimal pairs.
 EXAMPLE: /t/ and /p/ are two phonemes of English: ten and 
pen are two different words. Replacing /e/ by /I/ result in [tIn] and 
[pIn], therefore /e/ and /I/ are also two phonemes, etcetera. In Dutch the /e./ 
as in [be.t] (beet) and /e:/ as in [be:r] (beer) are not two 
phonemes since they cannot distinguish two words: *[be:t] and *[be.r].