what is noun?

In most language families, including English, nouns are the most common type of word. A noun is a term that describes something (a book), a people (Betty Crocker), an animal (a cat), a location (Omaha), a trait (softness), a concept (justice), or an activity (yodeling). It's generally a single word, but it's not always: nouns include cake, shoes, school bus, and hour and a half.
as an example, So, what is the proper term for butterflies as a group?