1 [always + adverb/preposition]T
to fasten something to something else with nails
nail something to something
A sign saying 'No Fishing' had been nailed to the tree.
nail something down
The lid was firmly nailed down.
nail something up (=permanently close a window or door by fixing something across it using nails)
The windows had been nailed up.
to catch someone and prove that they are guilty of a crime or something bad:
It took us 10 years to nail the guy who killed our daughter.
nail somebody for something
The state police finally nailed him for fraud.
if you nail something, you succeed in getting it, after a lot of time or effort:
She finally nailed her dream job.
4 British English informal
to prove that what someone has said is completely untrue
5PP British English
to say clearly and publicly which ideas or which people you support
6 especially American English
to punish someone severely
nail somebody/something ↔ downphrasal verb
to reach a final and definite agreement or decision about something:
Two days isn't enough time to nail down the details of an agreement.
to force someone to say clearly what they want or what they intend to do
nail somebody/something ↔ down to
Before they repair the car, nail them down to a price.