Germanic A-mutation - General Description

General Description

In a-mutation, a short high vowel (*/u/ or */i/) was lowered when the following syllable contained a non-high vowel (*/a/, /o:/ or /æ:/). Thus, since the change was produced by other vowels besides */a/, the term a-mutation is something of a misnomer. It has also been called "a-umlaut", "a/o-umlaut", "velar umlaut" and, formerly, "Brechung". (This last was Grimm's term, but nowadays German Brechung, and its English equivalents breaking and fracture, are generally restricted in use to other unrelated sound-changes which later affected individual Germanic languages)

• *hurnam → Old English horn "horn"
• *wiraz → Old English wer "man"

The high vowel was not lowered, however, if */j/ intervened between it and the following non-high vowel. An intervening nasal consonant followed by a consonant of any kind also blocked the process (and raised original */e/ to */i/).

• *gulþam → Old English gold "gold"
• *gulþ(i)janan → Old English gyldan "to gild" (with later i-mutation of u to y).

• *hundaz → Old English hund "dog"
• *swemmanan → Old English swimman "to swim"

a-mutation seems to have preceded the raising of unstressed final */o:/ to */u:/ in the dialects ancestral to Old English and Old Norse, hence in Old English the phenomenon is subject to many exceptions and apparent inconsistencies which are usually attributed to a mixture of paradigmatic levelling and phonetic context.