to change or alter, as in form, appearance, character, or substance

to vary one's methods.

to cause to be different from something else

The orchestra varied last night's program with one new selection.

to avoid or relieve from uniformity or monotony; diversify

to vary one's diet.

Music . to alter (a melody or theme) by modification or embellishments without changing its identity.

to show diversity; be different

The age at which children are ready to read varies.

to undergo change in appearance, form, substance, character, etc.

The landscape begins to vary as one drives south.

to change periodically or in succession; differ or alternate

Demand for certain products varies with the season.

to diverge; depart; deviate (usually fol. by from )

to vary from the norm.

Mathematics . to be subject to change.

Biology . to exhibit variation.

adjective

alternating , changeable , changing , deviating , differing , flexible , fluctuating , inconstant , irregular , shifting , uncertain , unstable , unsteady , vacillating , volatile , waffling , wavering