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(ŭn′dĕr-stāj″ing) Underestimation of the severity of a patient's illness, esp. an illness such as metastatic cancer. It can occur, for example, as a result of errors in pathological evaluation.


(ŭn′dĕr-ūs″) Failure to employ readily available forms of care for patients. SYN: underutilization.


(ŭn′dĕr-ūt″ĭl-ĭ-zā′shŏn) Underuse.


(ŭn″dĕr-vak″sĭ-nā′shŏn) Selective, partial, or delayed vaccination.

underwater weighing

A technique for the determination of a person's specific gravity. The person is placed under water, and the amount of water displaced by the person's body is corrected for the air contained in the lungs. This technique can be used to estimate the percentage of body fat. SYN: hydrodensitometry; hydrostatic densitometry; hydrostatic weighing. SEE: lean body mass.


(ŭn′dĕr-wāt″) Body weight for height that is 15% to 20% below healthy weight; a body mass index below 18.5 kg/m2. By this standard, which is the one promoted both by the World Health Organization and the National Heart, Lung, and Blood Institute, a person who stands 5′7″ tall is underweight if he or she weighs less than 120 lb.

In children, underweight can be defined as having a weight-for-height that is less than the 5th percentile for one's age.

undifferentiated connective tissue disease

ABBR: UCTD. A rheumatological disorder that does not fully meet the criteria for any of the well-defined rheumatological conditions such as rheumatoid arthritis, Sjögren syndrome, or systemic lupus erythematosus. Signs and symptoms of connective tissue disease must be present for several years. These may include polyarticular arthritis, Raynaud phenomenon, pleuritis, pericarditis, or symptoms of unexplained interstitial pneumonitis. The patient with UCTD will also have a positive antinuclear antibody test as well as other autoantibodies. Diagnostic difficulties in UCTD may be found in people who have evidence of mixed connective tissue disease or overlap syndrome. SEE: mixed connective tissue disease; overlap syndrome.


(ŭn-dĭf″ĕr-ĕn-shē-ā′shŭn) [AS. un, not, + L. differens, bearing apart] An alteration in cell character to a more embryonic type or toward a malignant state. SYN: anaplasia.


(ŭn′dyŭ-lănt, ′jŭ -) [L. undulare, to rise in waves] Rising and falling like waves, or moving like them.


(ŭn′dū-lāt) [L. undulatio, wavy] Wavy; having a wavy border with shallow sinuses, said of bacterial colonies.


(ŭn-dū-lā′shŭn) A continuous wavelike motion or pulsation.


(ŭn″fold′ing) In biochemistry, a synonym for the denaturation of a protein. SEE: denature (2).



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