Excessive; above normal.
[Greek huper, over or beyond.]
A person who is hypercritical is excessively and unreasonably critical, while someone or something hypersensitive is abnormally or exceedingly sensitive. Hyperbole (Greek ballein, to throw) is exaggerated statements or claims not meant to be taken literally. In medicine, hypertension is abnormally high blood pressure; hyperthermia is the condition of having a body temperature greatly above normal; a patient who hyperventilates breathes at an abnormally rapid rate.
The basis of the World Wide Web is hypertext, a tagging system that goes beyond text to allow cross-referencing between related material. A hypercube is a geometrical figure similar to a cube but in four or more dimensions; hyperspace is space of more than three dimensions, or in science fiction a notional space-time continuum in which it is possible to travel faster than light.
Hyper can also be a word in its own right—a shortening of hyperactive—for someone who is unusually energetic.