underweening adjective 1noun 1forms 2 adjective1 •Extremely modest.It is quite possible Challis may think you have an overweening estimate of foreigners and that a particular foreigner may think that your estimate of him is underweening as compared with his own. — 1995 noun1 •Undervaluation.Here is forbidden an over or underweening of the good things in our selves, — 1637 formsmore underweening · most underweening