Medical Dictionary: Glossary (H)

What is habitual abortion?

The miscarriage of 3 or more consecutive pregnancies.

What is hallucination?

It is a sensory experience in which a person can see, hear, smell, taste, or feel something that is not there.

What is handedness?

The preferential use of one hand for most manual tasks. Right handedness is the preferential use of the right hand while left handedness is the preferential use of the left hand for most manual tasks.

What is haploid?

A set of chromosomes that contains only one member of each chromosome pair. The sperm and egg are haploid and, in humans, each has 23 chromosomes.

What is heartburn?

A feeling of discomfort, burning and pain occurring in waves rising up behind the breastbone (sternum) toward the neck. It is usually due to gastroesophageal reflux disease (GERD), the rise of stomach acid back up into the esophagus.

What is hematoma?

A localized swelling that is filled with blood caused by a break in the wall of a blood vessel. The breakage may be spontaneous, as in an aneurysm, or caused by an injury.

What is hemorrhage?

Bleeding or the abnormal flow of blood.

What is heparin?

An anticoagulant (anti-clotting) medication. Heparin is useful in preventing thromboembolic complications (clots that travel from their site of origin through the blood stream to clog up another vessel).

What is hiccups?

A hiccup is an extraordinary type of respiratory movement involving a sudden inspiration (intake of air) due to an involuntary contraction of the diaphragm accompanied by closure of the glottis (the vocal apparatus of the larynx).