A word used as the designation or appellation of a creature or thing, existing in fact or in thought; a substantive.

names a person, an animal, a thing, a place, an event, or an idea

The user account name used to gain access to a computer system. Not a secret (contrast with Password).

the part of speech that is used to name a person, place, thing, quality, or action and can function as the subject or object of a verb, the object of a preposition, or an appositive.