This command is the opposite of the yesmen command - the AI will automatically (and almost instantly) decline any diplomatic offers, etc regardless of circumstances. Note that it affects AI response to AI offers as well (i.e. the AIs will decline all offers from other AI nations).
The syntax for the nomen command is as follows:
Find below working examples of the nomen command.
If nomen is disabled (default), running this command will enable it, making AI countries decline all offers made to them (including those from other AI nations). Running this command again, whilst nomen is enabled, will toggle it off.