Webster's New World Medical Dictionary

intelligence, verbal
The innate or learned abil-
ity to understand and answer questions given in
writing or verbally.
intelligence quotient
See 
IQ.
intelligence test
A questionnaire or series of
exercises designed to measure intelligence. There
are many types of intelligence tests, and they may
measure learning and/or ability in a wide variety of
areas and skills. Scores may be presented as an IQ
(intelligence quotient), as a mental age, or on a
scale.
intensive care
See 
critical care.
intensive care unit psychosis
See 
ICU psychosis.
intention tremor
An abnormal, repetitive shak-
ing movement of the body that appears during vol-
untary movement of a part of the body toward a
target. An intention tremor suggests a problem with
the cerebellum of the brain, the region important
for coordination and balance. See also 
tremor.
inter-
Prefix indicating between.
interatrial septum
The partition that separates
the upper chambers (atria) of the heart.
intercostal muscle
The muscle tissue between
any two ribs.
interferon
A naturally occurring substance that
interferes with the ability of viruses to reproduce.
Interferon also boosts the immune system. There
are a number of different interferons, and they fall
into three main classes: alpha, beta, and gamma. All
interferons are proteins (lymphokines) normally
produced by the body in response to infection.
Interferons can be synthesized using recombinant
DNA technology. See also 
interferon therapy.
interferon therapy
The administration of inter-
feron to help the body fight disease such as viral
infection or cancer. In therapeutic doses, interferon
can be hard to tolerate. Side effects include flu-like
symptoms (fatigue, headache, and aches) and, less
regularly, low thyroid activity, arthritis, low platelet
count, and severe depression. Some of these side
effects, particularly depression, can be successfully
treated with additional medications. See also 
inter-
feron.
interleukin
One of several similar protein sub-
stances that serve as signaling molecules within the
body. Interleukins can be produced by a variety of
different cells within the body and can be thought of
as chemical messengers that help regulate the
actions of the immune system. Abbreviated IL. They
may be used in biological therapy to stimulate the
growth and activities of certain kinds of white blood
cells that are involved in immune response.
Numerous different ILs have been identified.