Eldest

a.	1.	Oldest; longest in duration.
	2.	Born or living first, or before the others, as a son, daughter, brother, etc.; first in origin. See Elder. Their eldest historians are of suspected credit. - Bp. Stillingfleet. Eldest hand (Card Playing) the player on the dealer's left hand. - R. A. Proctor.

Noun	1.	eldest - the offspring who came first in the order of birth Synonyms: firstborn
Adj.	1.	eldest - first in order of birth; "the firstborn child" Synonyms: firstborn

ELDEST. He or she who has the greatest age.
     2. The laws of primogeniture are not in force in the United States; the eldest child of a family cannot, therefore, claim any right in consequence of being the eldest.

first, firstborn