hypertoxic UK /ˈhaɪ.pə(ɹ)ˈtɒk.sɪk/US /ˈhaɪ.pə(ɹ)ˈtɑk.sɪk/ adjective1 •(rare) Excessively toxic.We often find in insanity an inverse toxicity of the urine, and the blood, in mania especially, is as much more hypertoxic as the urine is hypotoxic. — 1832