A noun (from Latin nōmen, literally meaning "name")[1] is a word that functions as the name of some specific thing or set of things, such as living creatures, objects, places, actions, qualities, states of existence, or ideas.
Word classes (parts of speech) were described by Sanskrit grammarians from at least the 5th century BC. In Yāska's Nirukta, the noun (nāma) is one of the four main categories of words defined.[5]
The Ancient Greek equivalent was ónoma (ὄνομα), referred to by Plato in the Cratylus dialog, and later listed as one of the eight parts of speech in The Art of Grammar, attributed to Dionysius Thrax (2nd century BC).
Nouns have sometimes been defined in terms of the grammatical categories to which they are subject (classed by gender, inflected for case and number). Such definitions tend to be language-specific, since nouns do not have the same categories in all languages.
"Noun". Merriam-Webster Dictionary (online). Merriam-Webster, Incorporated. 2014.
Chicago Manual of Style, "5.10: Noun-equivalents and substantives
Proper nouns and common nouns
Countable and uncountable nouns
Collective nouns