Misnomer

A misnomer is a name that is incorrectly or unsuitably applied. Misnomers often arise because something was named long before its correct nature was known, or because an earlier form of something has been replaced by something to which the name no longer applies. A misnomer may also be simply a word that someone uses incorrectly or misleadingly. The word "misnomer" does not mean "misunderstanding" or "popular misconception", and a number of misnomers remain in common usage — which is to say that a word being a misnomer does not necessarily make usage of the word incorrect.
Sources of misnomers.
Some of the sources of misnomers are:
Examples.
Older name retained.
The term "anachronym" (note well "-chron-") as defined in Garner's Modern English Usage refers to this type of misnomer. Examples cited by Garner include the persistence of the word "dial" in its telephoning sense after the rotary dial era and the persistence of the term "tin foil" in the aluminum foil era. Anachronyms should not be homophonously confused with anacronyms (note well "-acro-"), which are words such as "laser" and "sonar" that have acronymic origin but are generally no longer treated like conventional acronyms (that is, they are used syntactically like any other words, without reference to their original expansions).