alsoknow something backwards British Englishknow something backwards and forwards American Englishto be very familiar with something, especially because you have learned about it or because you have a lot of experience:
formalused before you give someone information that they will be pleased to hear:
You will be pleased to know that we have accepted your offer.
it's ... Jim, but not as we know it
informal humorousused to say that something is completely different from what we would normally expect something of its type to be:
It's the blues Jim, but not as we know it.
➔ the next thing I/she etc knew
at next1 (6)WORD CHOICE: WORD CHOICE: know, find out, get to knowKnow means to have information about something• I know where you live. • I never knew you were such a good dancer.!! Do not use know when you mean to get information about something that you want to know. Use find out instead• I went to the window to find out what was happening outside (NOT I went to the window to know what was happening outside).Know also means to be familiar with someone or something• Do you know Sara well? • I don't really know London.!! Do not use know when you mean become familiar with someone or something. Use get to know instead• I'd like to get to know her better (NOT I'd like to know her better). • The best way to get to know Venice is by boat (NOT The best way to know Venice is by boat.)
Definition from the Longman Dictionary of Contemporary English Advanced Learner's Dictionary.