Definitions of variation:

• noun:   an activity that varies from a norm or standard

  Example: "Any variation in his routine was immediately reported"

• noun:   the act of changing or altering something slightly but noticeably from the norm or standard

  Example: "Who is responsible for these variations in taxation?"

• noun:   an artifact that deviates from a norm or standard

  Example: "He patented a variation on the sandal"

• noun:   a repetition of a musical theme in which it is modified or embellished
• noun:   an instance of change; the rate or magnitude of change
• noun:   (astronomy) any perturbation of the mean motion or orbit of a planet or satellite (especially a perturbation of the earth's moon)
• noun:   (ballet) a solo dance or dance figure
• noun:   something a little different from others of the same type
• noun:   (biology) an organism that has characteristics resulting from chromosomal alteration
• noun:   the angle (at a particular location) between magnetic north and true north