Entry 1 sense Webster, 1913 Harmaline /(här"mȧ*lĭn [or] -lēn)/ · Har·ma·line · IPA 01 n. An alkaloid found in the plant Peganum harmala. It forms bitter, yellow salts. 1. An alkaloid found in the plant Peganum harmala. It forms bitter, yellow salts.(Chem.)