know something backwards1 British EnglishBrE, know something backwards and forwards American EnglishAmEKNOW something to know something very well or perfectly 对某事了如指掌,熟知某事 She practiced her part until she knew it backwards and forwards. 她反复练习她的台词和动作,直到非常熟练。
→ know something backwards at backwards(3)
2 → know something inside out