This is the 777th most frequent Polish word.
całkowicie
Completely.
The word 'całkowicie' here emphasizes the full extent of the agreement.
Całkowicie się z Tobą zgadzam.
I completely agree with you.
In this case, 'całkowicie' is used to indicate the total novelty of the subject.
To jest coś całkowicie nowego.
This is something completely new.
Here, 'całkowicie' stresses the absolute degree to which the behavior cannot be accepted.