- capsule (n.)
- 1650s, from French capsule "a membranous sac" (16c.), from Latin capsula "small box or chest," diminutive of capsa "box, case, chest" (see case (n.2)). Medicinal sense is 1875; shortened form cap is from 1942. Sense in space capsule is first recorded 1954. As an adjective from 1938. Related: Capsular.