var·i·a·tion 
(vâr′ē-āshən, văr′-)
(vâr′ē-āshən, văr′-)n.
1.
a. The act, fact, or process of varying.
b. The extent or degree to which something varies: a variation of ten pounds in weight.
2. Something different from another of the same type: told a variation of an old joke. See Synonyms at difference.
3. Magnetic declination.
4. Biology The existence within a species or other group of organisms of differences in form, function, or behavior, especially when hereditary.
5. Mathematics A function that relates the values of one variable to those of other variables.
6. Music
a. A form that is an altered version of a given theme, diverging from it by melodic ornamentation and by changes in harmony, rhythm, or key.
b. One of a series of forms based on a single theme.
7. A solo dance, especially one forming part of a larger work.
var′i·ation·al adj.