- hypothesis - a tentative explanation or assumption of something not known or proven
- hypothermia - a condition in which the body's temperature drops below normal
- hypochondriac - a person who is excessively preoccupied with their health and overly sensitive to any perceived symptoms of illness
- hypodermic - pertaining to or located beneath the skin
- hypoglycemia - a condition characterized by abnormally low levels of blood sugar
- hypotenuse - the side opposite the right angle in a right triangle
- hypothyroidism-a condition characterized by an underactive thyroid gland
- hypothermia-a dangerously low body temperature