  We suggest a physical definition of the confinement mass scale in QCD in the
framework of non-perturbative, gauge invariant QCD, where all possible gluons
exchanged between any pair of quark lines are included; and we insist that a
stable, quark bound state should not and must not have transverse quark
fluctuations larger than the Compton wavelength of the bound state particle
itself. This is possible in our QCD formulation because there are two
parameters which describe confinement, a mass scale $\mu$, and a "deformation
parameter" $\xi$, which shrinks the transverse-quark-coordinate separation
distribution $\varphi(b)$ away from Gaussian. With the mass scale $\mu$ defined
as equal to the mass of each quark bound state, we show that $\xi$ decreases
with increasing bound state mass, $m_{BS}$, using order-of-magnitude estimates
which agree with obvious intuition. Our $\xi$-values, including a calculation
for the recently detected 4-quark system, display the predicted behavior: $\xi$
decreases with increasing $m_{BS}$. Our results for $\varphi(b)$, when the
quark bound state is a nucleon or heavier, then show agreement with the form of
Gaussian momentum-space fall-offs in recent Light-Front holographic analyses.
