covariant

[koh-vair-ee-uh nt]

adjective Mathematics.

(of one magnitude with respect to another) varying in accordance with a fixed mathematical relationship: The area of a square is covariant with the length of a side.

Origin of covariant

First recorded in 1850–55; co- + variant

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

We have in the Hessian the first instance of a covariant of a ternary form.
Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 8
Various