Are you looking for a way to tell someone they’ve gone too far, and you are angry? You could say that they’ve “crossed the line.” This post unpacks what this idiom means, where it came from, and how to use it.
Meaning
The idiom “to cross a line” means someone has overstepped, broken established rules, or broken unwritten social conventions.
“You have crossed a line” is the most common form.
When you tell someone they have crossed a line, you warn them and let them know you are angry. The line-crosser has offended you or broken your trust. You will remember that and may take further action.
Example Usage
Seeing an idiom in action is the best way to understand its meaning and usage. Take a look at these examples to discover how the saying “to cross the line” is usually used:
- “I’m a very understanding person, but I already warned you not to come home late multiple times, and now you stroll in at 2 am? You’ve really crossed the line this time! You’re grounded!”
- “You really crossed the line when you were rude to Mr Roberts, who’s been a regular customer for years. I’m afraid I’ll have to fire you.”
- “Some lines should never be crossed, and dating your ex’s sister is definitely one of those.”
- “Are you sure that’s a line you want to cross? You won’t be able to undo it!”
Origin
It is not entirely clear where the idiom “to cross the line” originated — several different theories exist.
The most commonly-accepted theory, which is also the most interesting, is related to a traditional practice among sailors.
The equator is a circle of latitude that divides the northern hemisphere from the southern hemisphere. It is represented as a straight line on world maps. Sailors who crossed this imaginary line for the first time traditionally celebrated the occasion with a ritual. This practice continues to this day.
The equator is represented by an invisible line — akin to the social conventions you may breach when you “cross the line.”
Other theories about the origin of this idiom include:
- Crossing the finish line while running a race
- Crossing a “line in the sand” — meaning a boundary someone has drawn.
It might also be helpful to imagine lines placed in public settings that require some privacy, such as banks, pharmacies, and post offices. Step over these lines before the last customer is finished, and you’ll definitely be rude.
Phrases Similar to Cross the Line
Instead of “you have crossed the line,” you can also say, “you have gone too far.” Other related phrases include:
- This is where I draw the line.
- Crossing the Rubicon — meaning passing a point of no return.
Phrases Opposite to Cross the Line
There are no antonyms for the idiom “to cross the line.” The opposite of crossing the line would be to behave in an acceptable manner.
You could describe such people as:
- Polite
- Humble
- Courteous
What Is the Correct Saying?
The correct saying is “to cross a line,” meaning to go too far or to overstep. “You have crossed the line” is the most common form.
Ways People May Say Cross the Line Incorrectly
If you associate crossing the line with finishing a race, you may assume that the idiom has a positive meaning (like “you have reached a milestone”).
That would be incorrect. Crossing the line does mean crossing a boundary, but a boundary you shouldn’t have crossed.
Acceptable Ways to Say Cross the Line
Has someone done something that really annoys you? You could tell them that they have crossed the line.
Are you worried that someone is about to make a decision they’ll regret? You could ask that person if they are sure they want to cross that line.
“Crossing the line” is a widely used and understood idiom. Most people will know what you mean when you use this phrase.