This is the 16287th most frequent Turkish word.
yapmaması
"Yapmaması" means "his/her/its not doing" or "not to do."
The word 'yapmaması' is used to describe Ali's lack of performing the action of completing the project. It implies a subject (Ali) and expresses negation of the action.
Ali'nin projeyi yapmaması bizi hayal kırıklığına uğrattı.
Ali's not completing the project disappointed us.
Here, 'yapmaması' refers to the action which was not supposed to be performed, modifying 'a mistake' to indicate the type of mistake discussed.
Yapmaması gereken bir hata, büyük sonuçlara yol açtı.
A mistake that should not have been made led to significant consequences.
In this sentence, 'yapmaması' refers to the habitual action of not exercising and how it impacts someone's health negatively.