Answer: metathesis

AnswerCrossword Clue
METATHESISTransposition, as cruel for crulle, Falstaff for Fastolph, etc.
metathesisA reaction in which two compounds exchange ions, typically with precipitation of an insoluble product
metathesisthe transposition within a word of letters, sounds, or syllables, as in the change from Old English brid to modern English bird or in the confusion of modren for modern
metathesisThe transposition of sounds or letters in a word