n.
1.a metaphor that has occurred so often that it has become a new meaning of the expression (e.g., `he is a snake' may once have been a metaphor but after years of use it has died and become a new sense of the word `snake')
Idiom of the Day
make nothing of (something)
to ignore something as if it had not happened
The woman made nothing of the fact that she almost hit a woman in the parking lot.