1. undeniable
undeniable proof
Love undeniably has wings to fly away from love, but it's also undeniable that it also has wings to fly back.
English word "impossible to deny"(undeniable) occurs in sets:
Słówka FCE (2011-07)2. irrefutable
Even today, his theory remains practically irrefutable.
It is the irrefutable evidence of the last 200 years.