Editing Old English (section)

=== Sound changes ===
{{Main|Phonological history of Old English}}
Some of the principal [[sound change]]s occurring in the pre-history and history of Old English were the following:
* Fronting of {{IPA|[ɑ(ː)]}} to {{IPA|[æ(ː)]}} except when [[nasal vowel|nasalised]] or followed by a [[nasal consonant]] ("Anglo-Frisian brightening"), partly reversed in certain positions by later "a-restoration" or retraction.
* Monophthongisation of the diphthong {{IPA|[ai]}}, and modification of remaining diphthongs to the [[height-harmonic]] type.
* Diphthongisation of long and short front vowels in certain positions ("breaking").
* Palatalisation of velars {{IPA|[k], [ɡ], [ɣ], [sk]}} to {{IPA|[tʃ], [dʒ], [j], [ʃ]}} in certain front-vowel environments.
* The process known as [[Germanic umlaut#I-mutation in Old English|i-mutation]] (which for example led to modern ''mice'' as the plural of ''mouse'').
* Loss of certain weak vowels in word-final and medial positions; reduction of remaining unstressed vowels.
* Diphthongisation of certain vowels before certain consonants when preceding a back vowel ("back mutation").
* Loss of {{IPA|/x/}} between vowels or between a voiced consonant and a vowel, with lengthening of the preceding vowel.
* Collapse of two consecutive vowels into a single vowel.
* "Palatal umlaut", which has given forms such as ''six'' (compare German {{lang|de|sechs}}).