What does the idiom "rack sb's brains" mean?

You are wondering about the meaning of the phrase rack sb's brains, maybe you heard it in a TV show, movie or theater play. Although this idiom is not used very often, it enriches your capacity of expression and strengthens communication. In which case is the expression rack sb's brains used and what is its meaning?

Meaning of "rack sb's brains"


The idiomatic expression "rack one's brains" is used to describe a process of thinking hard and long in order to come up with a solution or an idea. It suggests that someone is making a special effort to remember or recall something, or to think of an idea they couldn't think of before. Additionally, it can be used as a figure of speech to describe someone who is really struggling to come up with something, or is having difficulty in trying to remember something.


The phrase "rack one's brains" derives from the Old English verb "racian," meaning "to search or to strain oneself." By the 15th century, it had evolved into the phrase "to rake in one's brains," referring to the process of sifting through one's thoughts and memories. Over time, the second word was changed from "rake" to "rack," which is a more common and recognizable term for a process of straining or stretching oneself to remember something.


The idiomatic expression "rack one's brains" is mainly used in informal contexts, such as a conversation among friends or family. It can also be used in a more literal context, such as when someone is trying to figure out a problem or answer a difficult question. Additionally, it can be used sarcastically, as a way of making fun of someone who is having difficulty in coming up with a solution or answer.

Example Sentences

  • I've been racking my brains all morning trying to think of a solution to this problem.
  • He's been racking his brains for hours trying to remember the name of that actor.
  • I'm sorry, I can't think of a good answer - I've racked my brains and come up with nothing.
  • I don't know the answer, but I'll keep racking my brains until I do.

The meanings of the words in the "rack sb's brains" idiom

The Surprising Origins of Everyday English Idioms

Many English idioms have surprisingly dark origins, often rooted in violence, death, and superstition. For instance, the phrase "raining cats and dogs" is said to have originated in the 17th century, when heavy rain would often cause dead animals to wash up on the streets. Meanwhile, the idiom "rule of thumb" is believed to have originated from a law that allowed men to beat their wives with a stick no thicker than their thumb.


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