on no account idiom
C2 决不，绝对不;切莫
If something must on no account/not on any account be done, it must not be done at any time or for any reason.
Employees must on no account make personal phone calls from the office. 员工无论如何不能因为私事使用办公室电话。
These records must not on any account be changed. 这些记录无论如何都不能改动。