| Term | Definition |
| hyperacidity | excessive acidity |
| hypoglycemia | abnormally low level of sugar in the blood |
| hypertension | abnormally high blood pressure |
| hypotension | low blood pressure |
| hyperthermia | especially high fever |
| hypothermia | subnormal body temperature |
| hyperbole | exaggerated statements or claims not meant to be taken literally |
| hypersensitive | excessively sensitive |
| hypertrophy | enlargement of a body part or organ, as from excessive use |
| hypodermic | injected on the skin |
| hypothetical | assumed without proof for the purpose of reasoning |
| endo | within |
| exo | out of, outside |
| hyper | over, above |
| hypo | under, beneath |
| endogamy | marriage within the tribe, or social group |
| exogamy | marriage outside the tribe, or social group |
| endogenous | produced from within, due to internal causes |
| exogenous | produced from without; due to external causes |
| endoskeleton | internal skeleton or supporting framework in an animal |
| exoskeleton | hard protective structure developed outside the body, as the shell of a lobster |
| endoparasite | parasite living in the internal organs of an animal |
| exoteric | external; exterior; readily understandable |
| exotic | introduced from a foreign country; not native |