Meaning
To think very hard, straining to recall a fact, a name, or a solution. Typically found in continuous forms, as in 'I have been racking my brains all morning over that password', and it presents hard thinking as heavy, effortful work. Neutral register; Cambridge labels the idiom mainly UK, though it is common throughout the English-speaking world. Regional use: General English.
Origin
The rack here is the torture engine that stretched the body on a frame. The Phrase Finder documents the verb's path: 'rack' used of stretching or straining in 1553 ('They may not racke and stretche oute the rentes of their houses'), applied to the mind in 1583 by William Byrd ('Racke not thy wit to winne by wicked waies'), and attached specifically to brains by around 1680 in William Beveridge's sermons ('They rack their brains... they hazard their lives for it'); Shakespeare's Twelfth Night (1602) shows the verb's torment sense in 'How have the hours racked and tortured me'. On spelling, Merriam-Webster's usage guidance says 'rack', from Middle Dutch rekken, to stretch, is historically distinct from 'wrack', a word for wreckage and ruin, and recommends 'rack' for this idiom while acknowledging that 'wrack' has appeared as a variant for centuries.
Research Sources
References used to check this entry’s meaning, history, or documented forms.
Variants
- rack my memory
- rack one's brains
- rack your brain
- wrack your brains
Usage Examples
- I racked my brains for the name of the hotel, then found it on an old receipt.
- The committee racked its brains for a way to cut costs without layoffs.
- Detectives were racking their brains over the missing ledger until the accountant confessed.