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In Celtic linguistics, affection (also known as vowel affection or infection) is the change in the quality of a vowel under the influence of the vowel of the following, final syllable. Subsequently, the vowel triggering the change was normally lost.
The two main types of affection are a-infection and i-infection. i-infection is an example of i-mutation, and may be compared to Germanic umlaut. More rarely, the term "affection" (like "umlaut") may be heard applied to other languages, and is then a synonym for i-mutation generally.
- Benjamin W. Fortson, Indo-European Language and Culture: An Introduction. 2nd edition. Blackwell, 2010. ISBN 978-1-4051-8895-1, p. 317, 321, 328.