Webster's New World Medical Dictionary

burn, first degree
A superficial burn with simi-
lar characteristics to a typical sunburn. The skin is
red in color, without blistering, sensation is intact,
and the burn is usually somewhat painful.
burn, second degree
A burn severe enough to
cause blistering of the skin. The pain of a second-
degree burn is usually somewhat more intense than
the pain of a first-degree burn.
burn, third degree
A burn in which the damage
has progressed to the point of skin death. The skin
is white and without sensation. In extreme cases
damage may extend beyond the skin and into under-
lying tissue. In these cases the skin may be black-
ened or burned away. Unless skin grafts are feasible,
loss of the affected limb, permanent disfigurement,
and even death are likely in such severe cases.
burning mouth syndrome
An intense burning
sensation on the tongue, often at the tip of the
tongue. Burning mouth syndrome tends to develop
in “supertasters”—people with an unusually large
density of taste buds, each surrounded by pain
fibers—and in postmenopausal women, who may
lose their ability to sense bitter tastes as a result of
burning mouth syndrome.
burp 1
Gas brought up from the stomach through
the mouth, producing a guttural noise.
2
As a
verb, to bring up gas from the stomach through the
mouth. Also, to help a baby bring up gas after feed-
ing, by rubbing or patting its back. Also known as
eructation.
bursa
A closed, fluid-filled sac that functions as a
gliding surface to reduce friction between tissues of
the body. When a bursa becomes inflamed, the con-
dition is known as bursitis.
bursitis
Inflammation of a bursa, causing pain
and tenderness. See also 
bursa; bursitis, aseptic;
bursitis, calcific; bursitis, elbow; bursitis, hip;
bursitis, knee; bursitis, septic; bursitis, shoulder.