issuing of an order; command given
Refers to the act of giving an order or the moment an order is issued. Often used in formal, military, or organizational contexts.
See also: 一下
As soon as the order was given, the unit immediately began operations.
With a single order from the president, the project got underway.
命令 is a general term for an order or command. 命令一下 specifically emphasizes the moment or act of issuing the order.
号令一下 is similar but often used for a verbal command or signal, especially in group settings like sports or military drills.
Compound of 命令 (order, command) and 一下 (one stroke, once; here meaning 'as soon as something is done'). The 一下 part indicates the moment the order is given.