cit·rous \ˈsi.trəs\adjective Etymology: in sense 1, from New Latin Citrus; in sense 2, from citrus + -ous 1.: of or relating to the genus Citrus < a hardier strain of citrous trees > 2.: of, relating to, devoted to the production of, or affecting plants or fruit of the genus Citrus < a citrous disease > < an important citrous area >