leaguist /ˈliːɡɪst/adjective 1noun 1forms 3 adjective1 •Pertaining to membership of, or advocacy for, a league.Sazonov supported Hartwig's pro-Serbian and leaguist policy on the Balkans, as a means both of countering Austrian designs and applying indirect pressure to the Ottomans. — 2012 noun1 •A member or supporter of a league.In France the Leaguists began to denounce his rapacity and his nepotism; in Spain a Jesuit preached upon the lamentable state of the church. — 1837 formsleaguists · more leaguist · most leaguist