Plural

A plural word is one which by addition of an ending (in English, French, Spanish and Portuguese usually s) to a noun, represents more than one of that particular subject. In most languages it's directly opposed to the grammatical category of 'singular' but some languages have a third category, namely 'dual'.

A singular refers to one referent of a subject, while dual refers to two referents (especially for living creatures). A plural refers to more than those units of referents.

Some singular words do refer to collections, groups, organisations and institutions, but are considered as one entity: collective words and some plural words do refer to one single referent. For example the word "sheep" refers to both one individual sheep, as well as a flock of sheep; the amount referenced depends on the context of the word used.

In most languages the plural of words is marked in some way that makes it immediately clear to the audience that this category has been chosen.