[1870–75; appr(oval) + -o]This word is first recorded in the period 1870–75. Other words that entered Englishat around the same time include: Mafia, Victorian, giveaway, onshore, upgrade-o is a suffix occurring as the final element in informal shortenings of nouns (ammo; combo; condo; limo; promo); -o also forms nouns, usually derogatory, for persons or things exemplifying or associatedwith that specified by the base noun or adjective (cheapo; pinko; sicko; weirdo; wino)