1. A small soluble container, usually made of gelatin, that encloses a dose of an oral medicine or a vitamin.
2. Anatomy. A fibrous, membranous, or fatty sheath that encloses an organ or part, such as the sac surrounding the kidney or the fibrous tissues that surround a joint.
3. Microbiology. A mucopolysaccharide outer shell enveloping certain bacteria.
4. Botany.
   1. A dry dehiscent fruit that develops from two or more united carpels.
   2. The thin-walled, spore-containing structure of mosses and related plants.
5. A space capsule.
6. A brief summary; a condensation.

1. Highly condensed; very brief: a capsule description.
2. Very small; compact.

1. To enclose in or furnish with a capsule.
2. To condense or summarize: capsuled the news.

[French, from Latin capsula, diminutive of capsa, box.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.