n 1 a : a membrane or saclike structure enclosing a part or organ <the of the kidney> b : either of two layers or laminae of white matter in the cerebrum (1) : a layer that consists largely of fibers passing to and from the cerebral cortex and that lies internal to the lentiform nucleus - called also internal capsule (2) : one that lies between the lentiform nucleus and the claustrum - called also external capsule 2 : a shell usu. of gelatin for packaging something (as a drug or vitamins) : also : a usu. medicinal or nutritional preparation for oral use consisting of the shell and its contents 3 : a viscous or gelatinous often polysaccharide envelope surrounding certain microscopic organisms (as the pneumococcus) .
Similar sounding terms: cap·su·la
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