Webster's New World Medical Dictionary

bacteriostatic
Capable of inhibiting the growth
or reproduction of bacteria. See also 
bacteriocidal.
bacterium
Singular of bacteria. See also 
bacteria.
bag of waters
The amniotic sac and amniotic
fluid.
Baker cyst
A swelling in the space behind the
knee (the popliteal space) that is composed of a
membrane-lined sac filled with synovial fluid that
has escaped from the joint. Also known as synovial
cyst of the popliteal space.
balanitis
Inflammation of the rounded head (the
glans) of the penis. Inflammation of the foreskin is
called posthitis. In the uncircumcised male, balani-
tis and posthitis generally occur together as bal-
anoposthitis: inflammation of both the glans and
foreskin.
balanitis, circinate
A skin inflammation around
the penis in males with Reiter syndrome. With circi-
nate balanitis, the skin around the shaft and tip of the
penis can become inflamed and scaly. Cortisone
creams can be used as treatment. See also 
balanitis;
keratodermia blennorrhagicum; Reiter syndrome.
balanoposthitis
Inflammation of both the glans
penis and foreskin. An uncircumcised boy should
be taught to clean his penis with care to prevent
infection and inflammation of the foreskin and the
glans. Cleaning of the penis is done by gently
retracting the foreskin, only to the point where
resistance is met. Full retraction of the foreskin may
not be possible until after age 3. See also 
balanitis;
posthitis.
baldness
Lack or loss of hair on the scalp. Also
known as alopecia. There are many types of bald-
ness, each with a different cause. Baldness may be
localized to the front and top of the head, as in the
very common type of male-pattern baldness; bald-
ness may be patchy, a condition called alopecia
areata; or it may involve the entire head, as in alope-
cia capitis totalis. See 
alopecia; alopecia areata;
alopecia capitis totalis; alopecia, traumatic;
alopecia universalis.