Webster's New World Medical Dictionary

bite
In dental terms, how well the teeth fit
together (occlude) in the mouth.
bitewing X-ray
A dental X-ray that depicts how
the teeth fit together on one side of the mouth.
BKA
Below-the-knee amputation. See 
amputa-
tion.
Black Death
See 
bubonic plague.
black eye
Bruising of the eyelid and/or the area
around the eye as a result of trauma to the eye.
Colloquially known as a shiner.
black lung disease
A disease of the lungs that is
caused by inhaling coal dust, which in some patients
can lead to progressive massive fibrosis of the lungs
and severely impaired lung function. Also known as
anthracosis and coal miner’s pneumoconiosis.
Black Plague
See 
bubonic plague.
blackhead
A familiar term for what is medically
called an open comedo. A comedo, the primary sign
of acne, consists of a widened hair follicle filled with
skin debris, bacteria, and oil called sebum. A black-
head has a wide opening to the skin and is capped
with a blackened mass of skin debris. In contrast, a
closed comedo, commonly called a whitehead, has
an obstructed opening to the skin and may rupture
to cause a low-grade skin inflammatory reaction in
the area.
bladder
A hollow organ in the lower abdomen
that stores urine. The kidneys filter waste from the
blood and produce urine, which enters the bladder
through two tubes, called ureters. Urine leaves the
bladder through another tube, the urethra. In
women, the urethra is a short tube that opens just in
front of the vagina. In men, it is longer, passing
through the prostate gland and then the penis. Also
known as urinary bladder and vesical.
bladder, overactive
A condition in which sud-
den involuntary contractions of the muscular wall of
the bladder cause urinary urgency, immediate and
unstoppable needs to urinate. Overactive bladder is
a form of urinary incontinence (the unintentional
loss of urine) and is relatively common, particularly
in older adults. Treatment may include pelvic mus-
cle strengthening, behavioral therapy, and medica-
tions. Also called urge incontinence.
bladder cancer
A common form of cancer that
begins in the lining of the bladder. The most com-
mon warning sign is blood in the urine. Symptoms
include pain during urination, frequent urination,
and feeling the need to urinate without results. A
diagnosis of bladder cancer is supported by findings
in the medical history, physical examination, exam-
ination of the urine, and intravenous pyelogram