Meaning
Someone has at last understood or realized something, typically after a stretch of puzzlement during which the answer was in front of them. Almost always narrated about the moment of realization, and standard in British English rather than American. Informal and warm rather than insulting; it gently teases slow realization without questioning intelligence. Regional use: British English.
Origin
An allusion, in the Oxford English Dictionary's words as quoted by The Phrase Finder, to the mechanism of penny-in-the-slot machines. By 1890 such machines were everywhere and 'penny in the slot' was already proverbial: Word Histories cites the North-Eastern Daily Gazette of September 1890 on slot-metered gas supplies, and the Pall Mall Gazette of May 1890 on an automatic camera that worked three seconds after 'dropping the proverbial penny in the slot'. Because these machines often jammed, the wait for the coin to fall home before anything happened became the picture for delayed understanding. Word Histories locates the earliest figurative use yet found in the Derbyshire paper the Ripley and Heanor News of 10 April 1931: 'Then the penny dropped and I realised what it was'; the OED's own earliest citation is later, from the Daily Mirror of August 1939. Rival theories about coin-operated public toilet locks and about Button A and Button B telephone kiosks circulate, but The Phrase Finder finds no evidence for either, and reader anecdotes about Luddite warning pennies and slate miners are explicitly unverified.
Research Sources
References used to check this entry’s meaning, history, or documented forms.
Variants
- the penny drops
- the penny finally dropped
- the penny has dropped
- wait for the penny to drop
Usage Examples
- It took him three stations on the train before the penny dropped and he realized she had been flirting with him.
- When the auditor spelled out the duplicate invoices, the penny finally dropped with the whole board.
- You can explain a pun as slowly as you like; some listeners just have to wait for the penny to drop.