noun

1. a changing or being changed
2. a change, as in form, nature, qualities, etc.
3. Biol.
   1. a sudden variation in some inheritable characteristic in a germ cell of an individual animal or plant, as distinguished from a variation resulting from generations of gradual change
   2. an individual resulting from such variation; mutant
   3. an abrupt and relatively permanent change in somatic cells that is transmitted only to daughter cells and can be inherited only in plants that reproduce asexually
4. Linguis.
   1. umlaut (sense )
   2. alternation of consonants under specific conditions, as in variations in the initial consonant of a word in Irish and other Celtic languages

Etymology: ME mutacioun < OFr mutacion < L mutatio < mutare, to change: see miss