Bilateral has several meanings in the field of medicine.
The main definition is relating to or having two sides.
When describing organisms, bilateral symmetry refers to
the organism being divided into approximately mirror
image halves (identical shape on the left and right side).
Not all organisms have bilateral symmetry but most do
(such as humans) and those who do are referred to as
Bilateria. Some animals (e.g., starfish) have bilateral
symmetry in the earliest stage but not in the adult phase.
The brain has two sides (bilateral).
Bilateral also refers to something that appears or occurs on two sides, such as
something that affects both sides of the body. An example would be bilateral hearing
loss, in which the person has difficulty hearing in both ears. Another example is a skin
disease that occurs on both arms or both legs. Another definition of bilateral is affecting
both organs, if the organs are paired. The best examples of this would be a disease or
condition affecting both lungs or both kidneys. Bilateral also means having two layers.
Bilateralism is a condition in which two sides are the same in size, shape, or some other
Bilateral is often abbreviated in medical records as a B with a circle around it or as b/l.
Bilateral comes from the Latin word "bis" meaning "two," and the Latin word "latus"
meaning "side." Put the words together and you have "two side(s)."