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PHONOLOGY/PHONETICS: a feature which characterizes sounds that are produced by retracting the body of the tongue from its neutral position. EXAMPLE: the vowel [u] differs from [i] in that [u] is characterized by [+back] and [i] by [-back].

LIT.	Chomsky, N. and M. Halle (1968) Halle, M. & G. Clements (1983)