cata-, cat-, cath-, kata-

(Greek: down, downward; under, lower; against; entirely, in accordance with, completely; definitely)

1. A wild animal of the cat family; especially, the cougar or the lynx.
2. A mountain lion or "cat of the mountain".
catapedamania (s) (noun), catapedamanias (pl)
An impulse to jump from high places: Adam was an athlete who enjoyed climbing up mountains and gliding down with his parachute in catapedamanias to the valleys below whenever he has the opportunity to do them.
catapedaphobia (s) (noun), catapedaphobias (pl)
An abnormal fear of jumping from both high and low places: Ted and his child have a catapedaphobia that is related to a terror of heights, a harrow of falling, or apprehensiveness of being severely injured if it were to happen.
1. A speech disorder in which the same word is repeated several times in succession.
2. A stereotyped and meaningless repetition of words and phrases, as seen in some cases of schizophrenia.
Unnatural; contrary to nature.
cataplexy (s) (noun), cataplexies (pl)
1. A debilitating medical condition in which a person suddenly feels weak and collapses at moments of strong emotion; such as, laughter, anger, fear, or surprise: When such collapsing results, people with cataplexy may seriously injure themselves.

Sometimes, laughter and other emotions trigger a reflex of cataplexy in people which can bring many of the muscles of the body to the point of collapse.

The phenomenon of cataplexy can be measured by sending electric signals through the muscles and gauging their responses. In cataplexy, what is known as the H-reflex, a neurological pathway that causes muscle contractions, virtually disappears.

Cataplexy often happens to people who have narcolepsy, a disorder in which there is great difficulty stayin awake during the daytime.

2. Etymology: from Greek kata, "down" + plexis,"a stroke, a seizure," or "a falling-down seizure".
cataract (s) (noun), cataracts (pl)
The loss of transparency of the lens of the eye or a partial or complete opacity on or in the lens or capsule of one or both eyes which impairs vision or even causes some degree of blindness: A cataract usually doesn't cause complete blindness because even a densely opalescent lens that shows various colors will still transmit light; however, with the increasing loss of transparency, the clarity and detail of images will be progressively lost.

Cataracts usually occur in both eyes; however, in most cases one eye is more severely affected than the other eye.

Most people over the age of 65 have some degree of cataracts; but, usually the opacification is minor and it is often confined to the edges of the lens, or lenses, where it doesn't interfere with vision.

The term cataract came many centuries ago from the idea that the whiteness behind the pupil, or lens, was a kind of waterfall descending from the brain.

In fact, the appearance of the whiteness is a result of the changes in the delicate protein fibers within the lens in a way that is similar to what occurs in eggs when they are boiled.

—Compiled from excerpts located in
The American Medical Association Home Medical Encyclopedia,
Volume One; Medical Editor, Charles B. Clayman, M.D.;
Published by Random House, Inc.; New York; page 240.