A letter that has two or more pronunciations

WordNet Word definitions in WordNet
n. 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: polyphonic letter ]

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
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.

Wiktionary Word definitions in Wiktionary
n. A letter, or combination of letters, that can be pronounced in two or more different ways