authoritative
adj
1 having authority; that can be trusted; reliable 有权力的; 有权威的; 可相信的; 可靠的
information from an authoritative source 来自权威方面的消息.
2 given with authority; official 权威的; 官方的; 当局的
authoritative instructions, orders, etc 官方的指示, 命令等.
3 showing or seeming to show authority 显示权力的; 好像显示权威的
an authoritative tone of voice 权威式的口吻.