A capsule, in anatomy, is a cover or envelope partly or wholly surrounding a structure. Types of capsules include:

the sac which encloses the crystalline lens of the eye

the outer surface of a benign tumor

the shell of an egg (biology)

Glisson's capsule, a thin areolar coat of fibrous tissue lying inside the tunica serosa of the liver

joint capsules - every diarthrodial joint possesses a fibrous or ligamentous capsule, lined with synovial membrane, attached to the adjacent ends of the articulating bones

Bowman's capsules (or glomerular capsules) in the kidney substance

the renal capsule (also known as Gerota's fascia), a tough fibrous layer surrounding the kidney and covered in a thick layer of perinephric adipose tissue

the internal, external and extreme capsules of the brain