"Not one more word"
Translation:Pas un mot de plus
I was very curious about this myself so I posted a question on the WordRef forum and received this response from a native French speaker:
You can only use de plus after a noun when you mean: 1 more X, 2 additional Y's, etc.
► "Not one more word". → Pas un mot de plus. ✔
Pas un mot plus ✘ is simply not idiomatic.
It can also be used after an adverb. ► "Nothing more." Rien de plus.
As a standalone phrase, de plus means "moreover, besides".
There's also the phrase de plus en plus→ "more and more".