exposition (n.)

late 14c., exposicioun, "explanation, narration," from Old French esposicion "explanation, interpretation" (12c.) and directly from Latin expositionem (nominative expositio) "a setting or showing forth; narration, explanation," noun of action from past-participle stem of exponere "put forth; explain; expose," from ex "from, forth" (see ex-) + ponere "to put, place" (see position (n.)).

The meaning "public display" is attested by 1851 in reference to the Crystal Palace Exposition in London. Abbreviation Expo is recorded from 1963, in reference to planning for the world's fair held in Montreal in 1967.