nail down

British  

verb

1. to fasten down with or as if with nails

2. informal to extort a definite promise or consent from

   I nailed him down on the deadline

3. informal to settle in a definite way

   they nailed down the agreement

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nail down Idioms  

1. Establish conclusively, as in The reporter nailed down the story by checking all the facts. This metaphoric expression alludes to fixing or fastening something down with nails. [c. 1600]

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Example Sentences

The album’s closer, “Driftin’ Cowboy,” will nail down this collection for some as outright folk.

From The Wall Street Journal • Apr. 2, 2026

Their numbers are hard to nail down, but in the first half of 2025, nearly 4 in 10 new vehicle registrations were hybrid and EV variants.

From Los Angeles Times • Mar. 26, 2026

When Rupert’s children watched its too-close-for-comfort version of the chaos following Logan Roy’s sudden death, they leapt to nail down their family’s succession plan before it was too late.

From Salon • Mar. 14, 2026

EU-Swiss ties are currently governed by a patchwork of agreements, and the two have for years been striving to nail down a broader cooperation agreement.

From Barron's • Feb. 25, 2026

Then he threw the nail down and rested one ragged sneaker on the fish.

From "Mississippi Trial, 1955" by Chris Crowe