hypo-, hyp-

(Greek: under, below, beneath; less than; too little; deficient, diminished; used as a prefix)

A diseased state of the blood in which the quantity of fibrin is below normal.
1. A hypnotic agent that induces sleep.
2. An agent causing sleepiness or drowsiness.
Deficiency of acid; lack of normal acidity, as of the gastric juice.
hypoactive (adjective)
Less than normally active or under active: "The child's hypoactive behavior concerned the boy's parents and the doctor who examined him."
hypoactivity (s), hypoactivities (pl) (nouns)
Any abnormally decreased activity of the body or its organs; such as, the decreased cardiac output, thyroid secretion, or peristalsis: "The hypoactivities of the malnourished or starving children in areas of the world are obvious indications that they are going to die unless they are properly fed soon."
Decreased sharpness of sense perception.
hypoacusis (s) (noun), hypoacuses (pl)
Reduced or slightly impaired hearing which often involves neurosensory organs: "In the early 1930's, when Bill realized that he was experiencing hypoacusis, he could not afford a hearing aid; so, he put a small button on a string, put the button in his ear and the string in his pocket and, as a result, Bill noticed that people automatically spoke louder and so he had no trouble understanding them."
hypoadenia, hypadenia
Any deficiency in the function of a glandular organ or tissue.
A decreased sensitivity to pain.
1. Sickness or disturbances experienced in high altitudes due to reduced air pressure; high-altitude sickness.
2. Produced by reduced barometric pressure; not always distinguished from hypobarism and altitude sickness.