a thin pointed piece of metal with a flat top, which you hit into a surface with a hammer, for example to join things together or to hang something on:
The key was hanging on a nail by the door.
hammer/bang/hit a nail into something
She hammered a nail into the wall.
your nails are the hard smooth layers on the ends of your fingers and toes: ➔ fingernail, toenail
I've broken my nail.
Stop biting your nails!
She sat painting her nails (=putting a coloured substance on them).
He still had dirt under his nails.
one of several bad things which help to destroy someone's success or hopes:
Observers fear that this strike will be another nail in the coffin of the industry.
the final nail in his coffin
very tough and not easily frightened, or not caring about the effects of your actions on other people
a) British English
if you pay money on the nail, you pay it immediately
b) especially American English
They got it absolutely on the nail.