'Polyphone' definitions:

Definition of 'polyphone'

From: WordNet
noun
A letter that has two or more pronunciations; "`c' is a polyphone because it is pronounced like `k' in `car' but like `s' in `cell'" [syn: polyphone, polyphonic letter]

Definition of 'Polyphone'

From: GCIDE
  • Polyphone \Pol"y*phone\, n. A character or vocal sign representing more than one sound, as read, which is pronounced r[=e]d or r[e^]d. [1913 Webster]