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
lap up (something) or lap (something) up
to eat or drink something with the tongue (as a dog or cat would)
The dog lapped up the milk that his owner gave him.