Mis*no"mer (?), n. [OF. pref. mes- amiss, wrong (L. minus less) + F. nommer to name, L. nominare, fr. nomen name. See Name.] The misnaming of a person in a legal instrument, as in a complaint or indictment; any misnaming of a person or thing; a wrong or inapplicable name or title.

Many of the changes, by a great misnomer, called parliamentary "reforms".

The word "synonym" is fact a misnomer.

Mis*no"mer, v. t. To misname. [R.]

• An unsuitable or misleading name (for something).
       One of Robin Hood's merry men was Little John, whose name was a misnomer as he was supposedly over seven feet tall.
  
• (wjargon) A term whose sense in common usage conflicts with a technical sense.
        The term "koala bear" is often considered a misnomer because, unlike brown bears, grizzly bears and such, koalas are marsupials.
  
• Something that is not true; a myth.
       It is a misnomer that elephants are afraid of mice.