{v. phr.} To find out the real cause of. * /The superintendent talked with several students to get to the bottom of the trouble./ * /The doctor made several tests to get to the bottom of the man's headaches./ Compare: GET TO THE HEART OF.
GET TO THE BOTTOM OF
Meaning of GET TO THE BOTTOM OF in English
Dictionary of English idioms . Словарь английских идиом. 2012