frozen metaphor

Từ điển WordNet v3.1 - WordNet Dictionary

noun

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
• Hypernyms:
metaphor