Dead metaphor refers to a figure of speech that has lost its original meaning over time. It is a language used so often that people have forgotten its original meaning. Here are some synonyms for the term "dead metaphor." Firstly, cliche which is overused expression or idea that has lost its original impact. Secondly, stock phrase that is repeatedly used without any real thought or meaning. Thirdly, trope which is a recurring literary idea or motif. Fourthly, hackneyed which refers to anything that is excessively used or overfamiliar. Lastly, banality which is a trite, overused remark or idea that lacks creativity or originality. All in all, these synonyms describe the same phenomenon of language that has lost its originality or impact and is now dull and unimpressive.