Inelastic neutron scattering measurements on the itinerant antiferromagnet at a temperature of 8 K reveal two orthogonal planes of scattering perpendicular to the Co square lattice in reciprocal space, demonstrating the presence of effective one-dimensional spin interactions. These results are shown to arise from near-perfect bond frustration within the Heisenberg model on a square lattice with ferromagnetic and hence indicate that the extensive previous experimental and theoretical study of the Heisenberg model on local-moment square spin lattices should be expanded to include itinerant spin systems.