know (something) backwards

know (something) backwards

To be extremely familiar with a particular subject, field, or piece of writing, film, music, etc. Primarily heard in US, Australia. I've read this book so many times, I know it backwards. You should ask Samantha about the issue; she knows car engines backwards.
See also: backward, know

know something backwards

mainly BRITISH or

know something backwards and forwards

mainly AMERICAN
If you know a subject backwards, you know a lot about it. I thoroughly enjoy lecturing and know my subject backwards. He will be very much in demand. He knows the business backwards. They know company personnel policy backwards and forwards.
See also: backward, know, something