ablaut

noun

ab·​laut ˈä-ˌblau̇t  ˈa- 

ˈäp-ˌlau̇t

: a systematic variation of vowels in the same root or affix or in related roots or affixes especially in the Indo-European languages that is usually paralleled by differences in use or meaning (as in sing, sang, sung, song)

Word History

Etymology

borrowed from German Ablaut, from ab "down, from" (going back to Old High German ab, aba, preposition) + Laut "sound," going back to Middle High German lūt, going back to Old High German hlūtī, lūtī, liutī, derivative from the base of hlūt "loud, strident"; akin to Old English hlūd "loud" — more at of entry 1, loud

Note: As a term in Germanic and Indo-European comparative linguistics, ablaut was introduced in 1819 by Jacob Grimm in Deutsche Grammatik, vol. 1, p. 543. The word was used by earlier German grammarians pejoratively to refer to strong verbs—hence perhaps literally, "discordance," with ab- alluding to the deviation of the "irregular" strong verbs from "regular" weak verbs.

First Known Use

1838, in the meaning defined above