Wiktionary
zero-grade
n. (context Indo-European linguistics English) In Proto-Indo-European linguistics, a term used to describe an ablaut form of a root characterized by the absence of the basic ablauting vowel phonemes */e/ and */o/.
Usage examples of "zero-grade".
Suddenly the smell became a noise, easier to locate, coming from the wall to his right, down low, an ambiguous noise, maybe the sound of Grbk's zero-grade voice gargling out some stop consonants.