Misnomer

A misnomer is the wrong name or term for something; a misleading name, often idiomatic.

Some sources of misnomers include

A word used in ignorance of the true meaning.
An older name being retained as the thing named evolved (e.g., pencil lead, tin can, fixed income markets, mince meat pie, steamroller). This is essentially a metaphorical extension with the older item standing for anything filling its role.
A name being based on a similarity in a particular aspect (e.g. asteroids look like stars from Earth, the settled portions of Greenland are greener than the rest)
A difference between popular and technical meanings of a term. For example a koala "bear" looks and acts much like Ursid bears, but from a zoologist's point of view they are quite distinct. Similarly, fireflies fly, ladybugs look and act like bugs and peanuts look and taste like nuts. The technical sense is often cited as the "correct" sense, but this is a matter of context.
An older name being retained even in the face of newer information (e.g., Chinese checkers, Arabic numerals).
Ambiguity (e.g., a parkway is generally a road with park-like landscaping, not a place to park).

Examples

Animal crackers are not crackers but cookies.
Anti-Semitism is prejudice against Jews, not all Semites.
Arabic numerals originated in India, not in the Arab world.
Asteroids are small planets, not star-like objects as their name suggests.
In baseball, the statistic batting average is not an average but a percentage.
Chinese checkers is not Chinese (or even Asian) in origin.
A coconut is not a nut, but a dry fruit.
Crystalware glass, like all glass, is not a crystaline solid but an amorphous one.
The Democratic People's Republic of Korea is neither a democracy nor a republic and the same for the People's Republic of China and the Lao People's Democratic Republic (Laos)
One parks on a driveway and drives on a parkway.
Dry cleaning immerses clothes in liquid solvents that are anything but dry.
Fireflies are beetles, not flies, though they do fly.
Fixed income markets no longer deal predominately with fixed (known) payments.
Fullscreen is a term commonly used for home viewing releases (DVD, VHS, etc.) of theatrical films to differentiate from their widescreen counterpart. Yet, due to the rising popularity of 16:9 HDTV sets, it is, for the most part, the widescreen versions that are technically "fullscreen" (depending on their original aspect ratio.) Plus, most fullscreen versions of modern films, are in fact cut, zoomed, and panned versions of the original widescreen, so while the image fills a 4:3 screen, it is not in fact a "full" picture. The more correct term is "Pan and scan".
The fundamental theorem of algebra, though a theorem of algebra, may be proved by various non-algebraic means. This leads to the notion that it is "really" a theorem of analysis (or topology, etc.) and not of algebra. The deeper point that disparate fields of mathematics are connected in non-obvious ways remains valid, but designating the "fundamental theorem of algebra" a misnomer is debatable.
Greenland is mostly arctic and Iceland is mostly tundra.
The Hundred Years' War was actually a series of separate campaigns and battles which continued for 116 years (1337 to 1453).
Koala bears are marsupials not closely related to the Ursid family of bears.
The "lead" in pencils is made of graphite and clay, not lead, though lead was originally used for the same purpose.
Ladybirds, also known as ladybugs in American English, are neither birds nor bugs; they are beetles.
At Cambridge University, the May ball and May Bumps (boat race) take place in June.
A College lecturer in the University of Oxford is paid to give tutorials, not lectures (most lectures are in fact given by College tutors).
Newfoundland was considered newly found by those who so named it, but had first been inhabited at least 5,000 years before.
The Oktoberfest beer festival actually begins in September.
Panama hats are from Ecuador, not Panama.
Peanuts are legumes, not nuts.
Podcasting neither relates to just the iPod, nor does the technology involve any casting as the consumers pull audio data onto their audio players.
A radiator doesn't radiate, it works by convection.
Reduplication, a term in linguistics actually stands for duplication (and not fourfold repetition).
Scripting language is often used to describe the properties of some implementation of a programming language, or the original intent of the designer of the language, and not the language itself.
Tin foil are today almost always made of aluminium, whereas Tin cans made for the storage of food products are made from steel plated in a thin layer of tin.
The tremolo arm on guitars is used to produce vibrato; not tremolo. The correct term is "vibrato arm".
Catgut is made from sheep intestines.
Several sports teams' names are misnomers, including the Detroit Pistons (Auburn Hills not Detroit and the Washington Redskins who play in Landover, Maryland
Laramie, Wyoming is not in Laramie County though there is such a county in Wyoming
Kansas City is not exclusively in Kansas, but also in Missouri. See also Kansas City, Kansas

Examples

See also