Webster's New World Medical Dictionary

traction, orthopedic
The use of a system of
weights and pulleys to gradually change the position
of a bone. It may be used in cases of congenital
defect or bone and joint injury to prevent scar tissue
from building up in ways to limit movement and to
prevent contractures in disorders such as cerebral
palsy and arthritis.
trait 1
In genetics, a genetically determined char-
acteristic.
2
In medicine, a condition in the het-
erozygous state of a recessive disorder, as in sickle
cell trait.
3
In psychology, a characteristic pattern
of behavior.
tranquilizer
In pharmacology, a drug that calms
and relieves anxiety. The first tranquilizer, chlor-
diazepoxidehydrochloride (brand name: Librium),
received FDA approval in 1960. Tranquilizers range
in potency from mild to major, with increasing lev-
els of drowsiness occurring as potency increases.
They are prescribed for a wide variety of conditions
but are used primarily to treat anxiety and insomnia.
Most tranquilizers are potentially addictive, particu-
larly those in the benzodiazepine family.
trans-
Prefix meaning across, over, or beyond, as
in transplant operation (an operation in which an
organ from one person is grafted into another 
person).
trans fat
See 
trans fatty acid.
trans fatty acid
An unhealthy substance that is
made through the chemical process of hydrogena-
tion of oils. Hydrogenation solidifies liquid oils and
increases the shelf life and the flavor stability of oils
and foods that contain them. Trans fatty acids are
found in vegetable shortening and in some mar-
garine, crackers, cookies, and snack foods. Trans
fatty acids are also found in abundance in many
deep-fried foods. Trans fatty acids both raise the
“bad” (LDL) cholesterol and lower the “good”
(HDL) cholesterol levels in blood, markedly
increasing the risk of heart disease. Also known as
trans fat.