adjective: (category theory) (Of a functor) which preserves composition.
adjective: (object-oriented programming) Using or relating to covariance.
noun: (algebra) 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.
noun: (algebra) The variety defined by a covariant.
