a.

1. 必要的；紧急的；极重要的
   It is imperative to act now.

   现在必须行动起来。

2. 命令式的；必须服从的；专横的
   He made an imperative gesture.

   他做了个命令式的手势。

3. 【语】祈使法的
   the imperative mood

   祈使语气

n.

1. 必须履行的责任；必要的事；需要[C]
   Job creation has become an imperative for the government.

   创造就业机会成了政府必须做的事。

2. 命令；规则[C]
   follow the imperatives of history

   遵从历史规律

3. 【语】祈使语气[U]；祈使语气动词[C]

adj.

1. of vital importance.
2. giving an authoritative command.
   ▸Grammar  denoting the mood of a verb that expresses a command or exhortation, as in come here!

n.