Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† psalmus, i, m., = ψαλμός, i. q. psalma, a psalm (eccl. Lat.; cf.: carmen, hymnus), Tert. adv. Prax. 11; Lact. 4, 8, 14; 4, 12, 7; Vulg. Isa. 38, 20.
Esp., the Psalms of David, Vulg. Luc. 20, 42; id. Act. 13, 33 et saep.