noun
The act of varying; a partial change in the form, position, state, or qualities of a thing.
A related but distinct thing.
(nautical) The angular difference at the vessel between the direction of true north and magnetic north.
(board games) A line of play that differs from the original.
(music) 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.
(genetics) The modification of a hereditary trait.
(astronomy) Deviation from the mean orbit of a heavenly body.
(linguistics) 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.