variation

noun

Etymology: From Middle French variation, from Old French variacion, from Latin variātiō, from vary + -ation.

1. The act of varying; a partial change in the form, position, state, or qualities of a thing.

   “Plant breeding is always a numbers game.[…]The wild species we use are rich in genetic variation, and individual plants are highly heterozygous and do not breed true. In addition, we are looking for rare alleles, so the more plants we try, the better.”

2. A related but distinct thing.

   “When the process didn't work, we tried a variation.”

   “All of his soups are variations on a single recipe.”

3. The angular difference at the vessel between the direction of true north and magnetic north.
4. A line of play that differs from the original.
5. A technique where material is repeated with alterations to the melody, harmony, rhythm, timbre, texture, counterpoint or orchestration; but with some invariant characteristic, e.g. a ground bass.
6. The modification of a hereditary trait.
7. Deviation from the mean orbit of a heavenly body.
8. The situation where two or more linguistic forms appear in the same environment without a change in meaning, the choice of form being determined by factors of dialect, sociolect, register or simply the speaker's preference.
9. An infinitesimal perturbation applied to a function, typically denoted δf, used to probe how a functional changes.
10. The corresponding first-order change in a functional induced by such a perturbation, typically denoted δJ[f] and called the first variation.