syzygant

from The Century Dictionary.

• noun In algebra: The left-hand side of a syzygy.
• noun A rational integral function of the invariants or covariants of a quantic which, when expressed as a function of the coefficients, vanishes identically.
• noun An irreducible form of degree κ which becomes reducible when multiplied by αλ. Called the (κ + λ)ic syzygant.