Metaphors are figures of speech where something is described as being a different type of thing (e.g., the mitochondrion is the engine room of the cell) – to suggest some similarity.
Dead metaphors (or frozen metaphors) are terms that were once metaphorical, but which with repeated use have now been accepted as non-metaphorical labels.
Within a particular discourse community (within a scientific field, within a professional group) terms that were introduced metaphorically may acquire a 'frozen' meaning and come to be used as technical terms. They become dead metaphors within that community. However, a novice or nonspecialist from outside the group may perceive them as 'live' metaphors rather than dead metaphors that (now) have technical definitions. For the uninitiated, these are 'phantom' metaphors.
Read: 'Beware of phantom metaphors'
