1. ablaut - Noun
2. ablaut - Verb
The substitution of one root vowel for another, thus indicating a corresponding modification of use or meaning; vowel permutation; as, get, gat, got; sing, song; hang, hung.
Source: Webster's dictionaryA few verbs have palatalization in the active along with s in the 3rd singular, but no palatalization and no s in the mediopassive, along with no root ablaut (the vowel reflects PToch ë). Source: Internet
In addition, four subjunctive classes differ from the corresponding indicative classes, two "special subjunctive" classes with differing suffixes and two "varying subjunctive" classes with root ablaut reflecting the PIE perfect. Source: Internet
In the first three pairs of vowels, Bomhard is attempting to specify the subphonemic variation involved, inasmuch as that variation led to some of the vowel gradation ( ablaut ) and vowel harmony patterning found in various daughter languages. Source: Internet
In addition, nouns of e-stems have an ablaut of long vowel ė in nominative and short vowel e /ɛ/ in vocative. Source: Internet
Frequently mentioned is Esperanto's agglutinative morphology based on invariant morphemes, and the subsequent lack of ablaut (internal inflection of its roots ), which Zamenhof himself thought would prove alien to non-Indo-European language speakers. Source: Internet
Both root and suffix ablaut is still well-represented, although again with significant innovations. Source: Internet