Is it ensure, insure, or assure?
1640s, from Latin lymphaticus, from lympha (see lymph). Also sometimes used in the classical Latin sense "mad, frenzied," which was the primary sense of lymphaticus in Latin: OED reports this "difficult to account for," but perhaps due to association of lympha with nymphe; cf. Greek nymphian "to be frenzy-stricken."
lymphatic lym·phat·ic (lĭm-fāt'ĭk)
Of or relating to lymph, a lymph node, or a lymphatic vessel. n.
A lymphatic vessel.