misnomernoun [ C ]
uk/ˌmɪsˈnəʊ.mər/us/ˌmɪsˈnoʊ.mɚ/a name that does not suit what it refers to, or the use of such a name:
It was the scruffiest place I've ever stayed in, so "Grand Hotel" was a complete misnomer.
It's something of a misnomer to refer to these inexperienced boys as soldiers.