Plurale tantum

A plurale tantum (Latin for "plural only"; ) is a noun that appears only in the plural form and does not have a singular variant for referring to a single object. In a less strict usage of the term, it can also refer to nouns whose singular form is rarely used.
In English, "pluralia tantum" are often words that denote objects that occur or function as pairs or sets, such as "spectacles", "trousers", "pants", "scissors", "clothes", or "genitals". Other examples are for collections that, like "alms" and "feces", cannot conceivably be singular. Other examples include "suds", "jeans", "outskirts", "odds", "riches", "surroundings", "thanks", and "heroics".
In some languages, "pluralia tantum" refer to points or periods of time (for example, Latin 'calends, the first day of the month', German 'vacation, holiday') or to events (for example, Finnish 'wedding' and 'face'). In some cases there is no obvious semantic reason for a particular noun to be "plurale tantum". The Hebrew () 'water', Chichewa 'water', Dutch 'brain', Swedish and Russian () 'money' are "pluralia tantum".
A bilingual example is the Latin word that was brought into English; when referring to the symbol of authority, it is a "plurale tantum" noun in both languages.
English usage.
In English, some "plurale tantum" nouns have a singular form used only attributively. Phrases such as "trouser press" and "scissor kick" contain the singular form, but it is considered nonstandard to say "a trouser" or "a scissor" on its own. That accords with the strong preference for singular nouns in attributive positions in English, but some words are used in the plural form even as attributive nouns, such as "clothes peg", "glasses case" – notwithstanding "spectacle case" and "eyeglass case".
In English, a word may have many definitions only some of which are "pluralia tantum". The word "glasses" (a set of corrective lenses to improve eyesight) is "plurale tantum". In contrast, the word "glass"— either a container for drinks (a count noun) or a vitreous substance (a mass noun)— may be singular or plural. Some words, such as "brain" and "intestine", can be used as either "plurale tantum" nouns or count nouns.
Singulare tantum.
The term for a noun that appears only in the singular form is singulare tantum (plural: singularia tantum), such as 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." Such nouns may refer to a unique singular object (essentially a proper noun), but more often than not, they refer to uncountable nouns, either mass nouns (referring to a substance that cannot be counted as distinct objects, such as "milk") or collective nouns (referring to objects that may in principle be counted but are referred to as one, such as "popcorn" or Arabic 'mulberry'). Given that they do not have a number distinction, they may appear as "singulare tantum" in one language but as "plurale tantum" in another. Compare English "water" to the Hebrew "plurale tantum", ().
In English, such words are almost always mass nouns. Some uncountable nouns can be alternatively used as count nouns when meaning "a type of", and the plural means "more than one type of". For example, "strength" is uncountable in "Strength is power", but it can be used as a countable noun to mean an "instance" of [a "kind" of] strength, as in "My strengths are in physics and chemistry." Some words, especially proper nouns such as the name of an individual, are nearly always in the singular form because there is only one example of what that noun means.
Usage in other languages.
"Pluralia tantum" vary arbitrarily between languages. For example, in Swedish, a pair of scissors is just (literal translation "one scissor"), not a "plurale tantum"; similarly, in French, a pair of trousers is 'un pantalon'.
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 (one-"plural" glasses-"plural") or (one-"singular" pair-"singular" glasses-"genitive plural"). For larger quantities, "collective numeral" forms are available: (three doors), (five violins). Compare them to the ordinary numeral forms found in Polish: (three films/five films)
The Russian ( money) originally had a singular, (), which meant a copper coin worth half a kopeck.
The Yiddish word "kreplach" is a well known example of a plurale tantum that is also plural only in other languages into which it is borrowed, 'one of the kreplach' would be איינער פון די קרעפּלאַך (eyner fun di kreplakh).
The Welsh 'heaven' is the plural of which is no longer part of the spoken language. is now used with the singular meaning 'heaven' and plural 'heavens'.