= Covariance
{wiki}
= Covariant
{synonym}
Generally means that he form of the equation $f(x)$ does not change if we transform $x$.
This is generally what we want from the laws of physics.
E.g. a <Galilean transformation> generally changes the exact values of coordinates, but not the form of the laws of physics themselves.
<Lorentz covariance> is the main context under which the word "covariant" appears, because we really don't want the form of the equations to change under <Lorentz transforms>, and "covariance" is often used as a synonym of "Lorentz covariance".
TODO some sources distinguish "invariant" from "covariant": <invariant vs covariant>.