noun

1. 1. the act, fact, or process of varying; change or deviation in form, condition, appearance, extent, etc. from a former or usual state, or from an assumed standard
   2. the degree or extent of such change
2. declination (sense 3)
3. a thing that is somewhat different from another of the same kind
4. Astron. a change in or deviation from the mean motion or orbit of a planet, satellite, etc.
5. Ballet a solo dance
6. Biol.
   1. a deviation from the usual or parental type in structure or form
   2. an organism showing such deviation
7. Math. the manner in which two or more quantities change relative to one another
8. Music the repetition of a theme or musical idea with changes or embellishments in harmony, rhythm, key, etc., esp. any of a series of such repetitions developing a single theme

Etymology: ME variacion < OFr < L variatio