Webster's New World Medical Dictionary

international normalized ratio
A system
established by the World Health Organization
(WHO) and the International Committee on
Thrombosis and Hemostasis for reporting the
results of blood coagulation (clotting) tests.
Abbreviated INR. Under the INR system, all results
are standardized. For example, a person taking the
anticoagulant warfarin (brand name: Coumadin)
would regularly have blood tested to measure the
INR. The INR permits patients on anticoagulants to
travel and obtain comparable test results wherever
they are.
internist
A physician who practices internal
medicine and specializes in the diagnosis and 
medical treatment of adults. See also 
internal 
medicine.
interobserver variation
The amount of varia-
tion between the results obtained by two or more
observers examining the same material.
interphase
The interval in the cell cycle between
two cell divisions, during which the individual chro-
mosomes cannot be distinguished. Interphase was
once thought to be a resting phase, but it is actually
the time when DNA is replicated in the cell nucleus.
intersex
A group of conditions sometimes
referred to as disorders of sexual development
(DSDs) in which there is a discrepancy between the
appearance of the external genitalia and the type of
internal (testes and ovaries) genitalia. The condi-
tion was formerly termed hermaphroditism or
pseudohermaphroditism. One example of intersex
is androgen insensitivity syndrome, in which the
body’s receptors to male hormones do not function
properly. In this case, individuals have a male
genetic makeup (XY) and testicular tissue but have
incompletely formed or female external genitalia. In
some cases, known as true gonadal intersex, a per-
son has both ovarian and testicular tissue.
interstitial
Pertaining to being between things,
especially between things that are normally closely
spaced. The word interstitial is much used in medi-
cine and has specific meaning, depending on the
context. For instance, interstitial cystitis is a specific
type of inflammation of the bladder wall. Interstitial
radiation involves placing radioactive material
directly into a tumor. Interstitial pneumonia is
inflammation of the lung that involves the mesh of
lung tissue (alveolar septa) rather than the air
spaces (alveoli).