tooth and nail

adverb

1. with all one's resources or energy; fiercely:

   We fought tooth and nail but lost.

tooth and nail

1. To fight “tooth and nail” is to fight with the intensity and ferocity of a wild animal: “The resistance forces fought the invading troops tooth and nail.”

Word History and Origins

Origin of tooth and nail¹

First recorded in 1525–35

Example Sentences

Ms Byrne said she had seen pupils in their final years of secondary school who could "barely read and write" and had had to "fight tooth and nail" to get support for her own child.

From BBC

“Right now, currently, the Valley is just surviving, as is a lot of Los Angeles — just barely surviving and fighting for everything that they can, tooth and nail,” she told LA Progressive earlier this year.

From Los Angeles Times

We fight tooth and nail to keep this band together because we saw the way that U2 were.

From Los Angeles Times

“We’ve always had to fight tooth and nail for our place in this world,” the group said in a news release Wednesday.

From Seattle Times

"What's the purpose of life if what we're fighting tooth and nail to get away from is what finally hit us the hardest!?" he added on X.

From BBC