A plurale tantum (Latin for in the plural only; plural form: pluralia tantum) is a noun that appears only in the plural form and does not have a singular variant, though it may still refer to one or many of the objects it names. Many languages have pluralia tantum, such as the English words clothes, scissors, pants, and trousers, the Russian word "den'gi" [деньги] ("money"), the Swedish word inälvor ("intestines"), or the Dutch word hersenen ("brains").
The term for a noun which appears only in the singular form is singulare tantum (plural: singularia tantum), for example the English words "information", "dust" and "wealth". Singulare tantum is defined by the Shorter Oxford English Dictionary as: "Gram. A word having only a singular form; esp. a non-count noun." In the English language, such words are almost always uncountable nouns. In some non-count words, the plural means "more than one sort of". Some words are nearly always in the singular because only one example exists of what the noun means.
In many dialects of English, quantifying a plurale tantum noun requires a measure word, for example "one pair of scissors" instead of "one scissors". In other languages, special numeral forms are used in such cases. In Polish, for example, "one pair of eyeglasses" is expressed as either jedne okulary (one-plur. glasses-plur.) or jedna para okularów (one-sing. pair-sing. glasses-gen. plur.). For larger quantities, "collective numeral" forms are available: troje drzwi (three doors), pięcioro skrzypiec (five violins). Compare these to the ordinary numeral forms found in Polish: trzy filmy / pięć filmów (three films / five films)
In Estonian it is possible to say either paar pükse (a pair of trousers), where pükse is the genitive of the plurale tantum word püksid (trousers), or ühed püksid (literally "ones trousers"), using the plural form of the numeral üks (one).