operetta

n. 小歌剧

opening, opening night, opening-time, openly, openness, opera, opera-glasses, opera-house, operable, operate, operatic, operatically, operating system, operating-table, operating-theatre, operation, operational, operations room, operative, operator, ophthalmic, ophthalmic optician, ophthalmologist, ophthalmology, ophthalmoscope, opiate, opine, opinion, opinion poll, opinionated, opium, opossum, opp, opponent, opportune, opportunely, opportunism, opportunist, opportunistic, opportunity,