Skunked term

A skunked term is a word that becomes difficult to use because it is evolving from one meaning to another, perhaps inconsistent or even opposite, usage, or a word that becomes difficult to use due to other controversy surrounding the word. Purists may insist on the old usage, while descriptivists may be more open to newer usages. Readers may not know which sense is meant especially when prescriptivists insist on a meaning that accords with interests that often conflict.

The term was coined by the lexicographer Bryan A. Garner in Garner's Modern American Usage and has since been adopted by some other style guides.

Usage
Garner recommends avoiding such terms if their use may distract readers from the intended meaning of a text.

Some terms, such as "fulsome", may become skunked, and then eventually revert to their original meaning over time.

Terms with opposite meanings

 * Humbled originally meant "brought low" but is often used to mean "honored".
 * "It's all downhill from here" originally meant to become easier but is widely used to mean becoming worse or more difficult.
 * Literally is widely used with metaphorical language for emphasis.
 * A moot point in British English has historically meant a point that is worth debating, but the meaning is shifting towards that in US English of a point that is irrelevant or academic.
 * A "steep learning curve" was used in psychology from the 1920s to describe the quick and easy acquisition of skill; it was adopted more widely in the 1970s with the opposite meaning, describing a difficult and arduous process.

Terms with potential to offend

 * Niggardly means "miserly" or "parsimonious", but is rarely used in modern English because it is easily confused with the slur nigger, despite their separate etymologies.
 * Oriental originally referred to anything associated with the east or orient, including the Middle East, and including people. More recently, the term has come to refer to East Asia exclusively, and use of the word to describe people has become offensive.
 * The words faggot and fag have various meanings in British English (such as a faggot being a meat dish or a bundle of sticks, and a fag being a cigarette) but in the United States they are homophobic slurs.

Other terms

 * Biweekly has come to mean either "occurring every two weeks" or "occurring twice a week". The same ambiguity exists for the word bimonthly.
 * Data, and media have come to ambiguously describe both singular and plural entities, with the singular forms datum and medium declining in use.
 * Disinterested is widely used to mean "uninterested" whereas the primary meaning is "unbiased".
 * Drug can mean both pharmaceutical medicines and illegal recreational psychoactive substances like cocaine or heroin.
 * Hopefully used to mean "in a hopeful manner" but has come to mean "it is hoped" since the early 1960s.
 * Inflammable means "prone to catching fire", but is sometimes interpreted to mean "not flammable" due to the fact that the English prefix in- usually suggests "not". Due to potential dangers of the word confusion, inflammable has seen a decrease in usage in the last decades, while the word nonflammable is used instead to mean "not flammable".