Negative polarity item

A negative polarity item is an expression that is restricted to negative contexts and some other semantically related contexts such as questions and conditional clauses although its semantic properties would seem to allow occurrence in positive contexts as well.

Examples
English indefinite pronouns such as any, either, minimizers such as a fig, a drop, a wink, and verbal idioms such as lift a finger, budge an inch.

Negative polarity items are attested in most languages.

Contexts licensing negative polarity items
Negative polarity items are licensed inter alia in the following contexts:
 * Direct negation (I have'nt seen anybody.)
 * Indirect negation (I don't think that anybody will like this.)
 * Non-affirmative predicates (I doubt that he has done anything.)
 * Negative prepositions (They hired someone without any experience.)
 * Adversative predicates (I am surprised that anything so absurd could have been circulated.)
 * Restrictor of universal quantifier (Everyone who has any interest in linguistics...)
 * Restrictor of superlative (This is the most stupid question any person has ever asked.)
 * Comparative sentences (He was more exhausted than anyone else).
 * Predications of 'excess' with too (He was too exhausted to understand anything.)
 * The protasis of a conditional clause (If you need anything, let me know.)

Such contexts have inter alia been subsumed under the terms affective (Klima 1964), downward entailing (Ladusaw 1980) and nonveridival (Zwarts 1995).

Comments

 * “Since negative polarity items are not restricted to negative contexts..., this term (coined by Baker 1970) is not particularly felicitous. As the discussion in §5.5 will show, a term like scale reversal would be much more appropriate than negative polarity (and negative polarity items should be called scale reversal items).” (Haspelmath 1997:34)

Origin
The term was first used in print by Baker (1970), and must have been coined by him (Larry Horn, p.c. to Martin Haspelmath, 16 December 1992). Earlier authors who noted the phenomena just called them “facts restricted to negative contexts” (Buyssens 1959) or “constituents whose occurrence is favored by NEG” (Klima 1964:287).

Links
Utrecht Lexicon of Linguistics The Polarity Items Bibliography (University of Tübingen)