Quadrigeminal \Quad`ri*gem"i*nal\, Quadrigeminous \Quad`ri*gem"i*nous\, a. [Quadri- + L. gemini twins.] Fourfold; having four similar parts, or two pairs of similar parts. {Quadrigeminal bodies} (Anat.), two pairs of lobes, or elevations, on the dorsal side of the midbrain of most mammals; the optic lobes. The anterior pair are called the nates, and the posterior the testes.