foundationalist adjective 1noun 1forms 3 adjective1 •Of or relating to foundationalism. noun1 •A supporter of foundationalism, the doctrine that beliefs derive justification from certain basic beliefsSo the foundationalist holds that both experiences and beliefs can justify beliefs, whereas the coherentist holds that only beliefs can justify beliefs. — 2007 formsfoundationalists · more foundationalist · most foundationalist