Plural

The plural (sometimes abbreviated PL), in many languages, is one of the values of the grammatical category of number. Plural of nouns typically denote a quantity other than the default quantity represented by a noun, which is generally one (the form that represents this default quantity is said to be of singular number). Most commonly, therefore, plurals are used to denote two or more of something, although they may also denote more than fractional, zero or negative amounts. An example of a plural is the English word cats, which corresponds to the singular cat.

Words of other types, such as verbs, adjectives and pronouns, also frequently have distinct plural forms, which are used in agreement with the number of their associated nouns.

Some languages also have a dual (denoting exactly two of something) or other systems of number categories. However, in English and many other languages, singular and plural are the only grammatical numbers, except for possible remnants of the dual in pronouns such as both and either.

In many languages, there is also a dual number (used for indicating two objects). Some other grammatical numbers present in various languages include trial (for three objects) and paucal (for an imprecise but small number of objects). In languages with dual, trial, or paucal numbers, plural refers to numbers higher than those. However, numbers besides singular, plural, and (to a lesser extent) dual are extremely rare. Languages with numerical classifiers such as Chinese and Japanese lack any significant grammatical number at all, though they are likely to have plural personal pronouns.

...
Wikipedia