The pion decay constant $F_\pi$ plays an important role in QCD and in Chiral Perturbation Theory. It is hardly known, however, that a corresponding constant exists in the Schwinger model with $N_f\geq 2$ degenerate fermion flavors. In this case, the "pion" does not decay and $F_\pi$ is dimensionless. Still, $F_\pi$ can be defined by 2d analogies to the Gell-Mann$-$Oakes$-$Renner relation, the residual "pion" mass in the $\delta$-regime and the Witten-Veneziano formula. With suitable assumptions, simulation data inserted in these three QCD-inspired relations are all compatible with $F_\pi\simeq 1/\sqrt{2\pi}$ at zero fermion mass, and $N_f=2,…,6$. Therefore this constant seems to be meaningful in the Schwinger model.