Meaning of capsule: Capsule describes both the fibrous tissue enclosing an organ, joint, or tumor and the swallowable gelatin shelled form of many oral medications.

Definition of capsule

In anatomy, a capsule is a layer of fibrous tissue that surrounds and encloses a structure such as an organ, a joint, or a tumor. A joint capsule, for example, encloses the joint space and helps hold the bones in proper alignment, while an organ such as the kidney is surrounded by its own fibrous capsule.

Separately, capsule also names a common form used for oral medication, in which a dose of medicine is enclosed within a shell, most often made of gelatin or a plant based alternative, that dissolves after being swallowed to release its contents. Capsules can be formulated to release their contents quickly or, in some cases, gradually over time.

Although the anatomical and pharmaceutical uses of the word describe very different things, both share the underlying idea of an outer covering or shell that encloses and contains something within it.

Used in a sentence

The medication was available in capsule form for patients who preferred not to take a tablet.

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Good to know

An anatomical capsule surrounding an organ or joint and a medication capsule taken by mouth share only the general concept of an enclosing shell, since the two uses of the word describe otherwise unrelated things.

Word origin

Where “capsule” comes from

Formed from Latin capsula, a diminutive of capsa, meaning box or case.

For learning, not diagnosis. This glossary provides general educational information and is not a substitute for advice from a qualified healthcare professional. If you may be experiencing a medical emergency, contact local emergency services.