zetacism noun2 •A sound change converting a consonant into /z/, the voiced alveolar sibilant.In the Lettish language, which partakes altogether of a more modern character, the zetacism seizes the dentals, gutterals ^([sic]), sibilants and liquids […] — 1860 •The lack of a sound change in a language when languages in the same family undergo rhotacism.
