contragredientadj.

1853 Sylvester in Philos. Trans. (Royal Soc.) 143 i. 543 A system of variables is cogredient to another system when it is subject to undergo simultaneously therewith linear substitution of a like kind, and contragredient when it is subject to undergo linear substitution simultaneously therewith but of a contrary kind.

1880 G. S. Carr Synopsis Elem. Results Math. I. §1813.

1885 G. Salmon Lessons Mod. Higher Algebra (ed. 4) 120 Similarly the ray coordinates of different lines for the same system of reference are cogredient, but the axial coordinates are transformed by the inverse substitution, that is, are contragredient to the former.