The thin end of the wedge
Definition 1 of 1
Pro Tip 1/3Slippery Slope
Suggests a step that leads to a series of negative events, often irreversible. 
Allowing students to use phones in exams is the thin end of the wedge, next they'll want open book tests.
Pro Tip 2/3Small Cause
A minor or initial action that causes a significant impact over time. 
Skipping one class may seem innocent, but it's the thin end of the wedge for poor academic performance.
Pro Tip 3/3Idiomatic Warning
Used as a cautionary statement about the start of a potential problem. 
This minor leak is the thin end of the wedge for future plumbing disasters in the building.
Never forget "The thin end of the wedge"
Humans forget easily. That's why you should download WordUp: Smart reminders, word games, AI practice, and much more!
WordUp Chrome Extension
As you browse the web instantly look up words you don’t know.
Get Chrome Extension