What is the meaning of Covariant?

Which preserves the order of morphism composition: formally, which associates each morphism to a morphism .

Using or relating to covariance.

A bihomogeneous polynomial in x, y, ... and the coefficients of some homogeneous form in x, y, ... that is invariant under some group of linear transformations.

The variety defined by a covariant.

Source: wiktionary.org