trinundinus, a, um, adj. tres nundinae, of or belonging to three weekly market-days (very rare): trinundino die, after seventeen days, Macr. S. 1, 16, 34; v. trinus, II. B., and nundinus, III.

— Hence, adv.: trinundinō, = trinundino die, Macr. S. 2, 13, 7.