Webster's New World Medical Dictionary

dietitian
A person trained in the design and man-
agement of the diet in health and disease as, for
example, in diabetes.
differential diagnosis
Knowledge gained
through weighing the probability of one disease
against the probability of other diseases that might
account for a patient’s illness. For example, the dif-
ferential diagnosis of a runny nose includes allergic
rhinitis (hay fever), the abuse of nasal deconges-
tants, and the common cold. Abbreviated DDX. See
also 
diagnosis.
differentiation 1
The process by which cells
become progressively more specialized; a normal
process by which cells mature. Cells early in devel-
opment have the potential to develop into many dif-
ferent types of tissues of the body. Differentiation
occurs so the specific body tissues can form. Once
developed into a specific cell type, the cell has lost
its ability to differentiate into a cell for a different tis-
sue. 
2
In cancer, the difference in the maturity
(development) of the cancer cells in a tumor.
Differentiated tumor cells resemble normal cells
and tend to grow and spread at a slower rate than
undifferentiated or poorly differentiated tumor
cells, which lack the structure and function of nor-
mal cells and grow uncontrollably. 
3
The evolution
from an incomplete form of disease to a complete
form of disease.
diffuse idiopathic skeletal hyperostosis
A
form of degenerative arthritis characteristically
associated with flowing calcification along the sides
of the vertebrae of the spine. Abbreviated DISH.
DISH commonly includes inflammation (tendonitis)
and calcification of the tendons at their points of
attachment to bone. Anti-inflammatory medications
(NSAIDs), such as ibuprofen, can be helpful in
relieving both pain and inflammation. Also called
Forestier disease.