Within an effective field theory framework, we obtain an expression for the
next-to-leading term in the 1/m expansion of the singlet QQˉ QCD
potential in terms of Wilson loops, which holds beyond perturbation theory. The
ambiguities in the definition of the QCD potential beyond leading order in
1/m are discussed and a specific expression for the 1/m potential is given.
We explicitly evaluate this expression at one loop and compare the outcome with
the existing perturbative results. On general grounds we show that for quenched
QED and fully Abelian-like models this expression exactly vanishes.Comment: 19 pages, LaTeX, 1 figure. Journal version. Discussion refined,
misprints corrected, few references added; results unchange