On no account
Definition 1 of 1
Pro Tip 1/3Strong Warning
Used to emphasize that something is very important to avoid. 
On no account must you disclose these confidential details.
Pro Tip 2/3Absolute Prohibition
Indicates a strict command or rule that must not be broken. 
On no account can employees use company resources for personal gain.
Pro Tip 3/3Not Negotiable
Shows that there is no leeway or flexibility allowed in a situation. 
On no account should anybody leave the premises during the lockdown.