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.
mid-15c., transicion, in grammar, from Latin transitionem (nominative transitio) "a going across or over," noun of action from past-participle stem of transire "go or cross over" (see transient).
1845 in the biological sense "exhibiting or affected by metabolism," from German metabolisch (1839), from Greek metabolikos "changeable," from metabole "a change, changing, a transition" (see metabolism). Related: Metabolically.
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.
"change of substance, conversion of one substance into another," 1570s, originally in rhetoric, from Late Latin metastasis "transition," from Greek metastasis "a removing, removal; migration; a changing; change, revolution," from methistanai "to remove, change," from meta, here indicating "change" (see meta-) + histanai "to place, cause to stand," from PIE root *sta- "to stand, make or be firm." A rhetorical term in Late Latin for "a sudden transition in subjects," medical use for "shift of disease from one part of the body to another" dates from 1660s in English. Related: Metastatic.