Examples of dead metaphors include:
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", "look a gift horse in the mouth", "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.