the penny drops

Said when someone suddenly comes to realize or understand something. Once the penny dropped, I was horrified by my behavior. My mother certainly didn't deserve it. Will the penny ever drop on the urgency of environmental issues? We activists can't save the planet by ourselves! I was watching his expression as he read the will, so I could tell the moment the penny dropped that he had been disinherited by his father.

See also: drop, penny

the penny drops

mainly BRITISH

COMMON If the penny drops, someone finally understands or realizes something. In the end the penny dropped. That was why she sent us back. It's only recently the penny's begun to drop that, actually, the new job is probably better than the other one. Note: This expression probably refers to slot machines (= machines for playing games), which only operate when you put in a coin.

See also: drop, penny

Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012

the penny drops

someone finally realizes or understands something. informal, chiefly British

The image here is of the operation of a coin-operated slot machine.

See also: drop, penny

Farlex Partner Idioms Dictionary © Farlex 2017

the ˌpenny ˈdrops

(informal, especially British English) suddenly understand the meaning or significance of something: She never understands jokes. It usually takes about half an hour for the penny to drop. ♢ There was a long silence on the stage, and then the penny finally dropped — it was my turn to speak.

This is a comparison with the way a machine starts after a coin is inserted.

See also: drop, penny

penny dropped, the

One finally catches on to something. The term alludes to old-time machines in which one deposited a penny to obtain a piece of candy, which one received after the penny dropped all the way down. Dating from the 1950s, it is used more in Britain than in the United States but is still current. Alexander McCall Smith used it in The Right Attitude to Rain (2006): “I think he realises now that she’s never going to come back to him. It’s taken a long time, but the penny has finally dropped.”