swear up and down

swear up and down

To make a very serious, solemn pledge, especially that one is telling the truth. Janet has sworn up and down that she wasn't the one to betray me, and I believe her.

See also: and, down, swear, up

Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

swear up and down

AMERICAN

If someone swears up and down that something is true, they insist very strongly that they are telling you the truth. He swore up and down he was going to get the cash and bring it right back. I couldn't get it out of my head that maybe it was all part of his plan, although he swore up and down it wasn't. Note: The usual British expression is swear blind.

See also: and, down, swear, up

Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012