From zero + grade, as in gradation (“apophony”). Possibly after German Nullstufe.
zero-grade (plural zero-grades)
- (Indo-European linguistics) In Proto-Indo-European linguistics, an ablaut form of a root characterized by the absence of the basic ablauting vowel phonemes */e/ and */o/.
- *bʰr̥- is the zero-grade of the Indo-European root *bʰer- meaning “to carry, bear”.
- Synonym: (dated) vanishing grade
- Coordinate terms: e-grade / full-grade, o-grade, lengthened grade