Editing Germanic umlaut (section)

====I-mutation in Old English====
[[File:Vowels of proto-Old English and general change when i-mutated.png|thumb|The vowels and diphthongs of proto-Old English prior to i-mutation (in black) and how they generally changed under i-mutation (in red). Outcomes varied according to dialect; i-mutation of diphthongs is given for Early West Saxon as spelled in manuscripts due to uncertainty about the precise phonetic value of the graph.]]
I-mutation generally affected Old English vowels as follows in each of the main dialects.{{sfnp |Campbell |1959 |pp=112, 190–204, 288}} It led to the introduction into Old English of the new sounds {{IPA|/y(ː)/}}, {{IPA|/ø(ː)/}} (which, in most varieties, soon turned into {{IPA|/e(ː)/}}), and a sound written in Early West Saxon manuscripts as {{angbr|ie}} but whose phonetic value is debated.
{| class="wikitable"
|+ i-mutation
|-
!rowspan=2| Original
!colspan=3| i-mutated
!rowspan=2| Examples and notes
|-
!West Saxon
!Anglian
!Kentish
|-
| {{lang|ang|a}} || colspan="2" | {{lang|ang|æ, e}}
| {{lang|ang|æ, e}} > {{lang|ang|e}} || {{lang|ang|bacan}} "to bake", {{lang|ang|bæcþ}} "(he/she) bakes". {{lang|ang|a}} > {{lang|ang|e}} particularly before nasal consonants: {{lang|ang|mann}} "person", {{lang|ang|menn}} "people"
|-
| {{lang|ang|ā}} || colspan="3" | {{lang|ang|ǣ}}
|| {{lang|ang|lār}} "teaching" (cf. "lore"), {{lang|ang|lǣran}} "to teach"
|-
| {{lang|ang|æ}}
| colspan="3"| {{lang|ang|e}} || {{lang|ang|þæc}} "covering" (cf. "thatch"), {{lang|ang|þeccan}} "to cover"
|-
| {{lang|ang|e}} || colspan="3" | {{lang|ang|i}} || not clearly attested due to earlier Germanic {{lang|gem-x-proto|e}} > {{lang|gem-x-proto|i}} before {{lang|gem-x-proto|i}}, {{lang|gem-x-proto|j}}
|-
| {{lang|ang|o}} || colspan="3" | {{lang|ang|ø}} > {{lang|ang|e}}
|| Latin {{lang|la|olium}}, Old English {{lang|ang|øle}} > {{lang|ang|ele}}.
|-
| {{lang|ang|ō}}
| colspan="3" | {{lang|ang|ø̄}} > {{lang|ang|ē}}
| {{lang|ang|fōt}} "foot", {{lang|ang|fø̄t}} > {{lang|ang|fēt}} "feet".
|-
| {{lang|ang|u}} || colspan="2" | {{lang|ang|y}}
| {{lang|ang|y}} > {{lang|ang|e}} || {{lang|ang|murnan}} "to mourn", {{lang|ang|myrnþ}} "(he/she) mourns"
|-
| {{lang|ang|ū}}
| colspan="2"| {{lang|ang|ȳ}}
| {{lang|ang|ȳ}} > {{lang|ang|ē}} || {{lang|ang|mūs}} "mouse", {{lang|ang|mȳs}} "mice"
|-
| {{lang|ang|ea}} || {{lang|ang|ie}} > {{lang|ang|y}}
| colspan="2" | {{lang|ang|e}} || {{lang|ang|eald}} "old", {{lang|ang|ieldra}}, {{lang|ang|eldra}} "older" (cf. "elder")
|-
| {{lang|ang|ēa}}
|| {{lang|ang|īe}} > {{lang|ang|ȳ}}
| colspan="2" | {{lang|ang|ē}} || {{lang|ang|nēah}} "near" (cf. "nigh"), {{lang|ang|nīehst}} "nearest" (cf. "next")
|-
| {{lang|ang|eo}} || colspan="3" | {{lang|ang|io}} > {{lang|ang|eo}} || examples are rare due to earlier Germanic {{lang|gem-x-proto|e}} > {{lang|gem-x-proto|i}} before {{lang|gem-x-proto|i}}, {{lang|gem-x-proto|j}}. {{lang|ang|io}} became {{lang|ang|eo}} in most later varieties of Old English
|-
| {{lang|ang|ēo}} || colspan="3" | {{lang|ang|īo}} > {{lang|ang|ēo}}
|| examples are rare due to earlier Germanic {{lang|gem-x-proto|e}} > {{lang|gem-x-proto|i}} before {{lang|gem-x-proto|i}}, {{lang|gem-x-proto|j}}. {{lang|ang|īo}} became {{lang|ang|ēo}} in most later varieties of Old English
|-
| {{lang|ang|io}}
| {{lang|ang|ie}} > {{lang|ang|y}}
| colspan="2" | {{lang|ang|io}}, {{lang|ang|eo}}
| {{lang|ang|*fiohtan}} "to fight", {{lang|ang|fieht}} "(he/she) fights". {{lang|ang|io}} became {{lang|ang|eo}} in most later varieties of Old English, giving alternations like {{lang|ang|beornan}} "to burn", {{lang|ang|biernþ}} "(he/she) burns"
|-
| {{lang|ang|īo}} || {{lang|ang|īe}} > {{lang|ang|ȳ}}
| colspan="2" | {{lang|ang|īo}}, {{lang|ang|ēo}} || {{lang|ang|līoht}} "light", {{lang|ang|līehtan}} "illuminate". {{lang|ang|īo}} became {{lang|ang|ēo}} in most later varieties of Old English, giving alternations like {{lang|ang|sēoþan}} "to boil" (cf. "seethe"), {{lang|ang|sīeþþ}} "(he/she) boils"
|}

I-mutation is particularly visible in the inflectional and derivational [[Old English morphology|morphology of Old English]] since it affected so many of the Old English vowels. Of 16 basic vowels and diphthongs in [[Old English]], only the four vowels {{lang|ang|ǣ, ē, i, ī}} were unaffected by i-mutation. Although i-mutation was originally triggered by an {{IPA|/i(ː)/}} or {{IPA|/j/}} in the syllable following the affected vowel, by the time of the surviving Old English texts, the {{IPA|/i(ː)/}} or {{IPA|/j/}} had generally changed (usually to {{IPA|/e/}}) or been lost entirely, with the result that i-mutation generally appears as a morphological process that affects a certain (seemingly arbitrary) set of forms. These are most common forms affected:
*The plural, and genitive/dative singular, forms of consonant-declension nouns (Proto-Germanic (PGmc) {{lang|gem-x-proto|-iz}}), as compared to the nominative/accusative singular &ndash; e.g., {{lang|ang|fōt}} "foot," {{lang|ang|fēt}} "feet;" {{lang|ang|mūs}} "mouse," {{lang|ang|mȳs}} "mice." Many more words were affected by this change in Old English versus modern English, for example, {{lang|ang|bōc}} "book," {{lang|ang|bēċ}} "books;" {{lang|ang|frēond}} "friend," {{lang|ang|frīend}} "friends."
*The second and third person [[present tense|present]] [[Grammatical number|singular]] [[indicative mood|indicative]] of [[Germanic strong verb|strong verb]]s (Pre-Old-English (Pre-OE) {{lang|mis|*-ist}}, {{lang|mis|*-iþ}}), as compared to the [[infinitive]] and other present-tense forms &ndash; e.g. {{lang|ang|helpan}} "to help," {{lang|ang|helpe}} "(I) help," {{lang|ang|hilpst}} "(you sg.) help," {{lang|ang|hilpþ}} "(he/she) helps," {{lang|ang|helpaþ}} "(we/you pl./they) help."
*The [[comparative]] form of some [[adjective]]s (Pre-OE {{lang|mis|*-ira}} < PGmc {{lang|gem-x-proto|-izǭ}}, Pre-OE {{lang|mis|*-ist}} < PGmc {{lang|gem-x-proto|-istaz}}), as compared to the base form &ndash; e.g. {{lang|ang|eald}} "old," {{lang|ang|ieldra}} "older," {{lang|ang|ieldest}} "oldest" (cf. "elder, eldest").
*Throughout the first class of weak verbs (original suffix {{lang|mis|-jan}}), as compared to the forms from which the verbs were derived &ndash; e.g. {{lang|ang|fōda}} "food," {{lang|ang|fēdan}} "to feed" < Pre-OE {{lang|mis|*fōdjan}}; {{lang|ang|lār}} "lore," {{lang|ang|lǣran}} "to teach;" {{lang|ang|feallan}} "to fall," {{lang|ang|fiellan}} "to fell."
*In the abstract nouns in {{lang|ang|þ(u)}} (PGmc {{lang|gem-x-proto|-iþō}}) corresponding to certain adjectives &ndash; e.g., {{lang|ang|strang}} "strong," {{lang|ang|strengþ(u)}} "strength;" {{lang|ang|hāl}} "whole/hale," {{lang|ang|hǣlþ(u)}} "health;" {{lang|ang|fūl}} "foul," {{lang|ang|fȳlþ(u)}} "filth."
*In female forms of several nouns with the suffix {{lang|ang|-enn}} (PGmc {{lang|gem-x-proto|-injō}}) &ndash; e.g., {{lang|ang|god}} "god," {{lang|ang|gydenn}} "goddess" (cf. German {{lang|de|Gott}}, {{lang|de|Göttin}}); {{lang|ang|fox}} "fox," {{lang|ang|fyxenn}} "vixen."
*In i-stem abstract nouns derived from verbs (PGmc {{lang|gem-x-proto|-iz}}) &ndash; e.g. {{lang|ang|cyme}} "a coming," {{lang|ang|cuman}} "to come;" {{lang|ang|byre}} "a son (orig., a being born)," {{lang|ang|beran}} "to bear;" {{lang|ang|fiell}} "a falling," {{lang|ang|feallan}} "to fall;" {{lang|ang|bend}} "a bond," {{lang|ang|bindan}} "to bind." Note that in some cases the abstract noun has a different vowel than the corresponding verb, due to Proto-Indo-European [[ablaut]].

=====Notes=====
#The phonologically expected umlaut of {{IPA|/a/}} is {{IPA|/æ/}}. However, in many cases {{IPA|/e/}} appears. Most {{IPA|/a/}} in Old English stem from earlier {{IPA|/æ/}} because of a change called [[a-restoration]]. This change was blocked when {{IPA|/i/}} or {{IPA|/j/}} followed, leaving {{IPA|/æ/}}, which subsequently mutated to {{IPA|/e/}}. For example, in the case of {{lang|ang|talu}} "tale" vs. {{lang|ang|tellan}} "to tell," the forms at one point in the early history of Old English were {{lang|ang|*tælu}} and {{lang|ang|*tælljan}}, respectively. A-restoration converted {{lang|ang|*tælu}} to {{lang|ang|talu}}, but left {{lang|ang|*tælljan}} alone, and it subsequently evolved to {{lang|ang|tellan}} by i-mutation. The same process "should" have led to {{lang|ang|*becþ}} instead of {{lang|ang|bæcþ}}. That is, the early forms were {{lang|ang|*bæcan}} and {{lang|ang|*bæciþ}}. A-restoration converted {{lang|ang|*bæcan}} to {{lang|ang|bacan}} but left alone {{lang|ang|*bæciþ}}, which would normally have evolved by umlaut to {{lang|ang|*becþ}}. In this case, however, once a-restoration took effect, {{lang|ang|*bæciþ}} was modified to {{lang|ang|*baciþ}} by analogy with {{lang|ang|bacan}}, and then later umlauted to {{lang|ang|bæcþ}}.
#A similar process resulted in the umlaut of {{IPA|/o/}} sometimes appearing as {{IPA|/e/}} and sometimes (usually, in fact) as {{IPA|/y/}}. In Old English, {{IPA|/o/}} generally stems from [[a-mutation]] of original {{IPA|/u/}}. A-mutation of {{IPA|/u/}} was blocked by a following {{IPA|/i/}} or {{IPA|/j/}}, which later triggered umlaut of the {{IPA|/u/}} to {{IPA|/y/}}, the reason for alternations between {{IPA|/o/}} and {{IPA|/y/}} being common. Umlaut of {{IPA|/o/}} to {{IPA|/e/}} occurs only when an original {{IPA|/u/}} was modified to {{IPA|/o/}} by analogy before umlaut took place. For example, {{lang|ang|dohtor}} comes from late [[Proto-Germanic]] {{lang|gem-x-proto|dohter}}, from earlier {{lang|gem-x-proto|duhter}}. The plural in Proto-Germanic was {{lang|gem-x-proto|duhtriz}}, with {{IPA|/u/}} unaffected by a-mutation due to the following {{IPA|/i/}}. At some point prior to i-mutation, the form {{lang|gem-x-proto|duhtriz}} was modified to {{lang|gem-x-proto|dohtriz}} by analogy with the singular form, which then allowed it to be umlauted to a form that resulted in {{lang|ang|dehter}}.

A few hundred years after i-umlaut began, another similar change called double umlaut occurred. It was triggered by an {{IPA|/i/}} or {{IPA|/j/}} in the third or fourth syllable of a word and mutated ''all'' previous vowels but worked only when the vowel directly preceding the {{IPA|/i/}} or {{IPA|/j/}} was {{IPA|/u/}}. This {{IPA|/u/}} typically appears as {{angbr|e}} in Old English or is deleted:

* {{lang|ang|hægtess}} "witch" < PGmc {{lang|gem-x-proto|hagatusjō}} (cf. [[Old High German]] {{lang|goh|hagazussa}})
* {{lang|ang|ǣmerge}} "embers" < Pre-OE {{lang|mis|*āmurja}} < PGmc {{lang|gem-x-proto|aimurjǭ}} (cf. Old High German {{lang|goh|eimurja}})
* {{lang|ang|ǣrende}} "errand" < PGmc {{lang|gem-x-proto|ǣrundijaz}} (cf. [[Old Saxon]] {{lang|osx|ārundi}})
* {{lang|ang|efstan}} "to hasten" < archaic {{lang|ang|øfestan}} < Pre-OE {{lang|mis|*ofustan}}
* {{lang|ang|ȳmest}} "upmost" < PGmc {{lang|gem-x-proto|uhumistaz}} (cf. [[Gothic language|Gothic]] {{lang|got-Latn|áuhumists}})

As shown by the examples, affected words typically had {{IPA|/u/}} in the second syllable and {{IPA|/a/}} in the first syllable. The {{IPA|/æ/}} developed too late to break to {{lang|ang|ea}} or to trigger palatalization of a preceding velar.