Dead metaphor

A dead metaphor is a figure of speech, initially developed as a metaphor, that through extensive popular usage has become a mainstream idiom and lost its original, metaphorical application. Some dead metaphors have been used for so long and so commonly that their users do not even know the original significance of their figurative meanings. The English language contains tens of thousands of such dead metaphors, and in fact it would be hard for a language to form without them. (See: Semantic change.) The expression dead metaphor is also sometimes used in a derogatory sense to mean a cliché. However, a truly dead metaphor is one in which the original meaning is largely forgotten and not simply a cliché.

Some examples of dead metaphors include (the metaphoric or metonymic word is given in bold):

flowerbed
head teacher
forerunner
to run for office
to lose face
to lend a hand
to broadcast
pilot -- originally meant the rudder of a boat.
flair -- originally meant a sweet smell.
a computer mouse
fishing for compliments
seeds of doubt
catch her name
world wide web
tulip -- originally meant the eastern headdress, the turban.
turn-on
flared jeans
he ploughed through the car at traffic lights
foothills or the foot of a mountain
brow of the hill
branches of government
windfall gain
fly
kidney beans

Because the speaker often does not know the metaphor's literal meaning, the user understands the phrase as a complete semantic unit rather than as a metaphor, i.e. the entire phrase carries a meaning distinct from the sum of the meanings of its individual components.

For instance, horses once played an important part in human activities, but nowadays few people in the West have experience of them. Despite this, modern English is riddled with equine metaphors: "holding the reins of power", "trot it out", "take the bit between one's teeth", "be saddled with", "put him through his paces", "ride roughshod over", "flogging a dead horse", "give the whip hand", "hold your horses", "long in the tooth", "put out to pasture", "getting his oats" and so on. These may be considered dead metaphors as the historical equine-related meaning is generally not appreciated by the contemporary user.