can't nail (something) down

can't nail (something) down

Unable to complete, do correctly, or be certain of some task or thing. I've been working on my speech for an hour, but I can't seem to nail it down. They couldn't nail down the terms of their agreement. I know I've heard this song before, but I can't quite nail it down.
See also: down, nail
Farlex Dictionary of Idioms.
See also:
  • right on the nail
  • nail a lie
  • nail a/the lie
  • nail on
  • nail in
  • hit the nail on the head, to
  • by itself
  • get hold of the right end of the stick
  • beat on
  • beat on (something)