Wordnet 3.0
NOUN (1)
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');
[syn: dead metaphor, frozen metaphor]
WordNet (r) 3.0 (2006):
dead metaphor
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') [syn:
dead metaphor, frozen metaphor]