Welsh
Noun
defnyddiwr m (plural defnyddiwyr)
-  user
Mutation
| Welsh mutation | 
|---|
| radical | soft | nasal | aspirate | 
| defnyddiwr | ddefnyddiwr | nefnyddiwr | unchanged | 
| Note: Some of these forms may be hypothetical. Not every possible mutated form of every word actually occurs.
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