to try very hard to remember something or to solve a problem. I've racked my brain, but I just can't remember his name. Synonyms and related words. To memorize something, or to try to remember something.

What does racking brains mean?

: to think very hard in order to try to remember something, solve a problem, etc. I've been racking my brain, but I can't remember his name.

Is it racking or wracking my brain?

The spelling 'rack' is now used in all senses except for the seaweed called wrack. So it's "rack and ruin," … "racking my brains," and so on. Some other usage guides provide a way of dealing with this question that has a certain brutal charm: just stop using the word wrack.