malarial UK /məˈlɛəɹi.əl/US /məˈlɛɹi.əl/adjective 1noun 1forms 1 adjective1 •Of, relating to, or infected by malaria.His whole constitution was that of an emaciated, suffering man, malarial and gaunt. — 2019 noun1 •A person who has malaria. formsmalarials