a. [ L. triduanus, fr. triduum space of three days; tri- + dies day. ] Lasting three lays; also, happening every third day. [ R. ] Blount. [ 1913 Webster ]
(n)(Middle Ages) the nephew of the king of Cornwall who (according to legend) fell in love with his uncle's bride (Iseult) after they mistakenly drank a love potion that left them eternally in love with each other, Syn.Tristram