Origin and history of -ule

mathematical method of treating problems by the use of a system of algebraic notation, 1660s, from Latin calculus "reckoning, account," originally "pebble used as a reckoning counter," diminutive of calx (genitive calcis) "limestone" (see chalk (n.)). The modern mathematical sense is a shortening of differential calculus.

In medicine, the word also has been used from 1732 to mean kidney stones, etc., then generally for "concretion occurring accidentally in the animal body," such as dental plaque.

"small case, natural or artificial," 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)). The medicinal sense is by 1875; its shortened form cap is attested from 1942. The sense in space capsule is recorded by 1954, perhaps from the earlier sense of "shell of a metallic cartridge" (1864). As an adjective from 1938. Related: Capsular.