O字開頭的單詞或詞組
opusOmanobligatoryoutbreakorthodoxover-the-counteroff-limitsohoocclusionoutrageoccultobliviousotorhinolaryngologyoctetoffspringorchestrateOphidiaOklahomaorphanageovertureon arrivalobjectivenessornamentOxfordoursoctalon airoutdoorsOedipus complexonceoverchargeobsidianorder codeOct.outcomeon dutyonwardoutspokenonyxovertoverheardopposed