Particularly genetic variation; a marked deviation from the typical form or function.

an activity that varies from a norm or standard; "any variation in his routine was immediately reported"

an artifact that deviates from a norm or standard; "he patented a variation on the sandal"

the act of changing or altering something slightly but noticeably from the norm or standard; "who is responsible for these variations in taxation?"

a deviation from the traditional text

Periodic or sporadic changes or deviations within a process.

the act or process of varying, divergence in a characteristic from an average or norm. (Webster)