It is often used in scientific and medical terms to indicate something that is situated beneath something else, or a condition that is below normal.
Here are some examples of words that use the root "hypo":
* Hypoglycemia: Low blood sugar
* Hypothermia: Low body temperature
* Hypotenuse: The side of a right triangle opposite the right angle (literally, "under the tension" - referring to the stretched hypotenuse)
* Hypocrite: Someone who pretends to be something they are not (literally, "one who plays under the mask").
The root "hypo" can also be used in combination with other Greek roots to form new words. For example, "hypodermic" means "under the skin."