Swear Down
A British and Irish informal phrase meaning I promise or that is genuinely true.
“I swear down, I never touched your charger.”
Swear down adds strong assurance to a denial or claim. It may sound confrontational when repeated.
The expression is strongly associated with British urban speech and spread further through UK music, television, and social media.
I swear down
The standard full form.
swear down on my life
A stronger oath-like version.
swear it down
A less common variation.
What does swear down mean?
It means I promise or I am telling the truth.
Is it mainly British slang?
Yes, though online media has spread it internationally.
Is it formal?
No. It is highly informal.