1590s, "a small study in a cloister," from Medieval Latin carula "enclosure in a cloister in which to sit and read," which is of unknown origin; perhaps from Latin corolla "little crown, garland," used in various senses of "ring" (for example, in a c. 1330 description of Stonehenge: "þis Bretons renged about þe feld, þe karole of þe stones beheld"); extended to precincts and spaces enclosed by rails, etc. Specific sense of "private cubicle in a library" is from 1912.