Well, what about not being reliant on docs for syntax, but only for library functions? I can never remember what each language calls "length" (length? size? Is it the same for strings and arrays? What about number of keys in a map?) but I don't feel too bad about that, even in languages I use every day.

On the other hand, if I have to look up the syntax for a loop, then I can't say I know the language yet.