Misnomer

mis·no·mer   (mĭs-nō'mər)    n.   An error in naming a person or place. Application of a wrong name. A name wrongly or unsuitably applied to a person or an 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 Indo-European roots).] mis·no'mered adj.

misnomer 

Main Entry: mis·no·mer
Pronunciation: "mis-'nO-m&r
Function: noun
Etymology: Anglo-French mesnomer, from mesnomer to misname, from Middle French mes- wrongly + nommer to name, from Latin nominare, from nomin- nomen name
: the misnaming of a person in a legal document or proceeding (as in a complaint or indictment); specifically : the institution of proceedings against and service of process on the correct party using the incorrect name —compare IDEM SONANS
NOTE: Amendment of the pleadings is generally allowed in cases of misnomer.