A plurale tantum (Latin for "plural only"; plural form: pluralia tantum) is a noun that appears only in the plural form and does not have a singular variant for referring to a single object. These are used in English for objects that function as pairs or sets (glasses, pants, scissors, clothes, electronics, bagpipes, genitals). Many languages have pluralia tantum, such as the Latin word Kalendae, the Russian word den'gi [деньги] ("money"), the Swedish word inälvor ("intestines"), or the Dutch word hersenen ("brains").
English usage 
In English, some plurale tantum nouns in fact have a singular form, but one that is used only attributively. That is, phrases such as "trouser presses" and "scissor kick" contain the singular form, even though it is considered non-standard to say "a trouser" on its own. This accords with a general preference for singular nouns in attributive positions in English; however, some words are used in the plural form even as attributive nouns (e.g. "clothes peg", "glasses case"). In some instances, singular forms of plurale tantum noun such as "a pant" or "a trouser" may be encountered. This form may be encountered when the item being referred to is a product, for example "the company were looking to market a new trouser to over-45s".
In most forms of English, quantifying a plurale tantum noun requires a measure word, for example "one pair of scissors" instead of "one scissors".
Some words, such as "brain" and "intestine", can be used as either pluralia tantum or as count nouns.
Related terms 
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. Some non-count nouns can be alternatively used as count nouns meaning "a type of", in which case the plural means "more than one type of" (for example, strength is uncountable in Strength is power but can be used as a countable noun meaning type of strength as in My strengths are in physics and chemistry). Some words - especially proper nouns, such as the full name of an individual - are nearly always in the singular because only one example exists of what the noun means.
Usage in non-English languages 
Pluralia tantum vary arbitrarily between languages. For example, Swedish en sax ("a pair of scissors") is not a plurale tantum, while in English it is (scissors).
In some other languages, rather than quantifying a plurale tantum noun with a measure word, 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)
See also 
|Look up plurale tantum in Wiktionary, the free dictionary.|