backwards and forwardsfirst in one direction and then in the opposite direction, usually many times
[TahlilGaran] Dictionary of Contemporary English ▲
backwards and forwards{adv. phr.} To the full extent; in all details; thoroughly; completely.
He understood automobile engines backwards and forwards. He knew basketball rules backwards and forwards. I explained matters to him so that he understood backwards and forwards how it was. [TahlilGaran] English Idioms Dictionary ▲