No, it is a verb. It means to discover or find out.
the detective attempted to ascertain the truth through his questioning of the suspect. Should you ascertain that a rumor is true before you believe in it?
I have yet to ascertain the knowledge required to become a lawyer.
The word "ascertain" is a verb. It means to find out something with certainty.
Later today I will ascertain whether my order has been shipped yet.
Guess
Can I check the BBB to ascertain if this is a legitimate business?
The word "ascertain" appears on page 112 in "And Then There Were None" by Agatha Christie.
percervere
To be certain about what you found out or learned
Verb.
ascertain, reassure, and maybe to make sure...
Pegasus, Arion