1. 权威性的　 generally regarded as providing knowledge or information that can be trusted
2. 专断的，命令式的　 having or showing authority; demanding or deserving respect and obedience

　～ dictionary　权威性的词典
　～ manner　威严的态度
　～ tone of voice　权威式的口吻

　This piece of news came from an authoritative source.　这条消息来自权威人士。
　David speaks in authoritative tones.　大卫以命令的口吻说话。
　His words are the most authoritative among the specialists.　这几个专家当中他的话最有权威。
　Don't be so authoritative when you ask me to do something.　你求我做事情时别用这种命令的口吻说话。
　Authoritative orders came to the ambassador from the president.　大使收到了总统下达的正式命令。

　［派生词］ authoritatively adv.权威地；专断地‖authoritativeness n.权威性；专断
　［同义词］ accepted, faithful, learned, official
　［反义词］ unreliable, unofficial