Literally: morning – command – evening – reform / change
Alternately: An unstable situation where it’s never clear what the rules are or what they’re going to be, because they’re being changed so frequently. Laws or decrees being issued in the morning and changed in the evening of the same day. Harmful waffling.
Notes: Some people write homophonic character 礼, “ceremony,” “thanks,” in place of 令, but this is considered an error.
This compound is derived from a passage in the Book of Han; accordingly, the compound can also be read kanbun-style as 朝に令して暮れに改む (ashita ni rei shite kure ni aratamu), “command in the morning, change in the evening.”