This is the 16155th most frequent Turkish word.
vermemeniz
"Your not giving" or "for you not to give."
The word 'vermemeniz' is used in a clause to indicate not giving, and 'meniz' connects the root verb with the subject respectfully.
Kitapları arkadaşınıza vermemeniz gerektiğini söylemişti.
He said that you shouldn't give the books to your friend.
Here, 'vermemeniz' modifies 'karar' (decision), suggesting the act of not giving a decision.
Bu konuda karar vermemeniz daha iyi olurdu.
It would have been better if you did not decide on this matter.
In this context, 'vermemeniz' conveys the act of not disclosing something important, referring here to 'secret'.