c. 1600, "part or character one takes," from French rôle "part played by a person in life," literally "roll" (of paper) on which an actor's part is written, from Old French rolle (see roll (n.)). Not originally in English with direct reference to actors and the stage, but figurative of them. The meaning "any conspicuous function performed characteristically by someone" is by 1875. In the social psychology sense is from 1913. Role model, one taken by others as a model in performance of some role, is attested by 1957.

1540s, "pertaining to marriage, nuptial," also "pertaining to the relationship of husband and wife," from French conjugal (13c.), from Latin coniugalis "relating to marriage," from coniunx (genitive coniugis) "spouse," which is related to coniugare "to join together," from assimilated form of com "with, together" (see con-) + iugare "to join," from iugum "yoke" (from PIE root *yeug- "to join"). Related: Conjugacy; conjugality.

also role-play, "act or condition of behaving as another would behave in a certain situation," 1958, from the verbal phrase, "to act out the role of" (by 1949); see role (n.) + play (v.). Related: Role-playing

Old English freondscipe "friendship, mutual liking and regard," also "conjugal love;" see friend (n.) + -ship. Similar formation in Dutch vriendschap, German Freundschaft, Swedish frändskap.

also re-cast, c. 1600, "to throw again," from re- "back, again" + cast (v.). Sense of "to cast or form anew, remodel," especially of literary works and other writing, is from 1790. Meaning "compute anew" is by 1865. Theater sense of "assign an actor or role to another role or actor" is by 1951. Related: Recasting. As a noun, "a fresh molding, arrangement, or modification," by 1840.

by 1979, initialism (acronym) from role-playing game (see roleplay). As an initialism for rocket-propelled grenade, by 1970.

"An actress whose role is decorative rather than histrionic" [OED], by 1833, from show (n.) + girl. Earlier "a pretty, talented girl; girl fit to model styles or behavior," by 1816.

coined 1959, from magneto- + sphere. So called because it is the region around the earth (and some other planets) in which the magnetic field of the planet plays a dominant role in the motion of particles.

late 14c., "ruler of a Muslim country," from Old French caliphe (12c., also algalife), from Medieval Latin califa, from Arabic khalifa "successor" (from khalafa "succeed"). The title given to the successor of Muhammad as leader of the community and defender of the faith; the first was Abu-Bakr, who succeeded Muhammad in the role of leader of the faithful after the prophet's death.

Old English þæs, variant of þas (which became those and took the role of plural of that), nominative and accusative plural of þes, þeos, þis "this" (see this). Differentiation of these and those is from late 13c. OED begins its long entry with the warning, "This word has a complicated history."