Placeholder name
Placeholder names are words that can refer to objects or people whose names are temporarily forgotten, irrelevant, or unknown in the context in which they are being discussed.
Linguistic role
These placeholders typically function grammatically as nouns and can be used for people (e.g. John Doe, Jane Doe), objects (e.g. widget) or places (e.g. Anytown, USA). They share a property with pronouns, because their referents must be supplied by context; but, unlike a pronoun, they may be used with no referent—the important part of the communication is not the thing nominally referred to by the placeholder, but the context in which the placeholder occurs.
Stuart Berg Flexner and Harold Wentworth's Dictionary of American Slang (1960) use the term kadigan for placeholder words. They define "kadigan" as a synonym for thingamajig. The term may have originated with Willard R. Espy, though others, such as David Annis, also used it (or cadigans) in their writing. Its etymology is obscure—Flexner and Wentworth related it to the generic word gin for engine (as in the cotton gin). It may also relate to the Irish surname Cadigan. Hypernyms (words for generic categories; e.g. "flower" for tulips and roses) may also be used in this function of a placeholder, but they are not considered to be kadigans.
