A can of worms is a situation that turns out to have many problems: touch one, and others appear. Open a can of worms means start that chain: changing the seating plan opened a can of worms about who should sit together. It's informal; a whole new can of worms is a whole new set of problems.
When would you say a can of worms?
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open / open up a can of worms; a whole new can of worms
- Changing the seating plan opened a can of worms about who should sit together.
- The missing receipt turned out to be a can of worms involving several old orders.
- I do not want to open a whole new can of worms during the final meeting.
What changed
First versionRevising one old rule opened a can of worm.
RevisionRevising one old rule opened a can of worms.
A problem feels like one thing, so the singular slips in: a can of worm. But the can is full of worms: a can of worms.
A hard nut to crack is a difficult problem on its own. A can of worms is a problem that brings new ones. Let sleeping dogs lie means don't stir up an issue while it's quiet.
Your turn
Complete the idiom for an issue that produces many complications: That question could open a can of ___.
Show the answer
worms — There are many worms in the can, so the idiom always uses worms.
Describe a small issue that unexpectedly led to a pile of problems, using open a can of worms.
Moving the weekly meeting opened a can of worms because three teams had arranged their schedules around it.
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