Idiom B2 Informal / Semi-formal

Let bygones be bygones

To forgive and forget past quarrels; to agree to move on from old disagreements

Meaning

Let bygones be bygones — To forgive and forget past quarrels or offences; to agree to stop being angry about something that happened in the past and to move on without holding a grudge.

Origin & History

The key word here is bygones, which simply means 'things gone by' or past events — from the older English combination of 'by' and 'gone'. The proverb built around it dates to the 16th and 17th centuries, when it appeared in collections of English sayings as a plea to let past offences remain in the past.

The expression became firmly established as a fixed proverb and has changed very little over the centuries. Today it is used wherever people decide to set aside an old conflict — in personal relationships, in business, and in diplomacy — keeping its original sense that what is done is done and should not be dragged into the present.

Example Sentences

SentenceContext
After years of not speaking, the two brothers decided to let bygones be bygones and meet for dinner.Family reconciliation
Let's let bygones be bygones and start the new project as a team.Workplace fresh start
She was willing to let bygones be bygones, but he kept bringing up the old argument.One-sided forgiveness
The two countries agreed to let bygones be bygones and reopen trade talks.Diplomatic relations
I know we fell out last summer, but can we let bygones be bygones?Repairing a friendship
Rather than seek revenge, she chose to let bygones be bygones.Choosing forgiveness

How to Use It

This idiom works in both informal conversation and semi-formal contexts such as journalism and diplomacy. It is most often used when proposing reconciliation — frequently with the structure let's let bygones be bygones or decided / agreed to let bygones be bygones. It implies a mutual willingness to move on, so it suits situations where both sides are ready to forgive rather than one person being forced to.

Common Mistakes

Mistakes to Avoid

Let bygone be bygone and move on.

Let bygones be bygones and move on. — The fixed form always uses 'bygones' (plural) twice; never 'bygone'.

We should let the bygones be bygones.

We should let bygones be bygones. — Do not add 'the'; the idiom has no article.

Let goneby be goneby about the argument.

Let bygones be bygones about the argument. — The word is 'bygones', not 'goneby'; the order is fixed.

Similar Idioms

Forgive and forget Bury the hatchet Wipe the slate clean Water under the bridge All Idioms →

Practise This Idiom

Flash Cards Flip Tiles

Practice English Idioms

Use these exercises to master idioms in context:

Flip Tiles Find the Match Idioms Quiz

Frequently Asked Questions

What does "Let bygones be bygones" mean?
"Let bygones be bygones" means to forgive and forget past quarrels. It describes a decision to stop being angry about something that happened in the past and to move on without holding a grudge.
Where does the idiom "Let bygones be bygones" come from?
The word 'bygones' simply means 'things gone by' or past events. The proverb dates back to the 16th and 17th centuries and carries the idea that past offences should be allowed to remain in the past rather than be dragged into the present.
Can you give an example of "Let bygones be bygones" in a sentence?
Here is an example: "After years of not speaking, the two brothers decided to let bygones be bygones and meet for dinner." — used when people agree to forgive past disagreements and reconcile.
Is "Let bygones be bygones" formal or informal?
It can be used in both informal and semi-formal contexts. It is common in everyday conversation about reconciliation, and also appears in diplomacy, journalism, and writing when describing a decision to move past old conflicts.
What CEFR level is "Let bygones be bygones"?
This idiom is typically taught at B2 level. It is an upper-intermediate expression that appears frequently in spoken English, journalism, and informal writing about forgiveness and reconciliation.
What are common mistakes with "Let bygones be bygones"?
A common mistake is changing the word 'bygones' to 'bygone' or 'goneby'. The fixed form always uses 'bygones' twice. For example: Let bygone be bygone is incorrect. The correct form is: Let bygones be bygones.
What idioms are similar to "Let bygones be bygones"?
Similar idioms include: Forgive and forget, Bury the hatchet, Wipe the slate clean, Water under the bridge. These share the idea of putting past conflicts behind you and moving on.
How do I practise idioms like "Let bygones be bygones"?
LexFizz's Flash Cards and Flip Tiles exercises are great for practising English idioms. Try writing your own example sentences using the idiom in context, and listen for it in films, podcasts, and conversations.
Can "Let bygones be bygones" be used in writing?
Yes. It works well in informal writing and journalism. Avoid it in formal academic writing unless you are intentionally quoting or discussing the idiom itself. In opinion pieces, blogs, and pieces about reconciliation it is a natural and expressive choice.
Does "Let bygones be bygones" have the same meaning in British and American English?
Yes, "Let bygones be bygones" is understood in both British and American English with the same meaning: to forgive and forget past quarrels. The idiom is widely recognised across all major varieties of English.