A dead metaphor is a figure of speech which has lost the original imagery of its meaning by extensive, repetitive, and popular usage, or because it refers to an obsolete technology or forgotten custom.
Because dead metaphors have a conventional meaning that differs from the original, they can be understood without knowing their earlier connotation.
[2] A distinction is often made between those dead metaphors whose origins are entirely unknown to the majority of people using them (such as the expression "to kick the bucket") and those whose source is widely known or symbolism easily understood but not often thought about (the idea of "falling in love").
[3] In addition, philosophers such as Colin Murray Turbayne and Kendall Walton have outlined the manner in which "dead metaphors" may continue to exert influence upon a user's thoughts long after their metaphorical properties have seemingly vanished.
Their research illustrates the manner in which "dead metaphors" have often become incorporated into accepted scientific and philosophical theories while also contributing to considerable obfuscation of thought over time.