quidam

Etymology
From.

Noun

 * 1) A nobody; a person of no importance.

Noun

 * 1) a person whose identity is not indicated, in a conversation, a writing
 * 2) individual
 * 1) individual

Etymology
From. Compare.

Pronoun

 * 1) someone, a certain one/thing; something

Usage notes
Not to be confused with.

Adjective

 * 1) a certain (person or thing), some (person or thing), one (in the sense of "a specific" person or thing not previously introduced in the present discourse)