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

Instead, nail down the parts that are boring.

From Barron's

Christopher loved his father, but it felt like being nailed down, pinioning them both to the ground.

From Literature

The Herdmans stole everything that wasn’t nailed down, just out of habit.

From Literature

"But with Hubble's Advanced Camera for Surveys, we're able to nail down that there's nothing there."

From Science Daily

"There's a term called 'RuneScapiness' which is a little bit hard to nail down," game designer Molly Mason told the BBC.

From BBC