Webster's New World Medical Dictionary

antiplatelet agent
A medication that interferes
with the tendency of platelets in the blood to clump
and clot. Aspirin is an antiplatelet agent.
antiseptic
Discouraging the growth of microor-
ganisms. Commonly refers to antiseptic prepara-
tions used during medical procedures or used to
maintain sanitary conditions in nursing homes, bar-
bershops, tattoo parlors, and other facilities where
unchecked microorganism growth could result in
disease. See also 
aseptic.
antispasmodic
A medication that relieves, pre-
vents, or lowers the incidence of muscle spasms,
especially those of smooth muscle such as in the
bowel wall.
antitoxin 1
An antibody that is naturally produced
to counteract a toxin, such as a toxin from a bacter-
ial infection or snake bite.
2
An antibody from the
serum of an animal stimulated with specific antibod-
ies that is administered to humans or other animals
to provide passive immunity to a disease. Such anti-
toxins are of short-term value only and are used for
treatment rather than prevention.
antiviral agent
A medication or another agent
that kills viruses or inhibits their capability to repro-
duce.
antro-duodenal motility study
A study used to
detect and record the contractions of the muscles of
the stomach and duodenum in order to diagnose
motility disorders of the stomach and small intes-
tine. A tube is passed through the nose, throat,
esophagus, and stomach, until the tip lies in the
small intestine. The tube senses when the muscles of
the stomach and small intestine contract and
squeeze it. The contractions are recorded by a com-
puter and analyzed.
antrum
A general term for a nearly closed cavity
or chamber. For example, the antrum of the stom-
ach (gastric antrum) is a portion before the outlet,
which is lined by mucosa and does not produce
acid. The paranasal sinuses can be referred to as
the frontal antrum, ethmoid antrum, and maxillary
antrum.