mis·no·mer 
(mĭs-nōmər)
(mĭs-nōmər)n.
1. An error in naming a person or place.
2.
a. Application of a wrong name.
b. A name wrongly or unsuitably applied to a person or object.
[Middle English misnoumer, from Old French mesnomer, to misname : mes-, wrongly; see MIS-1 + nommer, to name (from Latin nōmināre, from nōmen, name; see n-men- in the Appendix of Indo-European roots).]
mis·nomered adj.