Webster's Revised Unabridged Dictionary · 1913

Cousin

Cousin (kuz"'n) , noun

[French cousin, Late Latin cosinus, cusinus, contr. from Latin consobrinus the child of a mother's sister, cousin; con- + sobrinus a cousin by the mother's side, a form derived from soror (for sosor) sister. See Sister, and compare Cozen, Coz.]

1.
One collaterally related more remotely than a brother or sister; especially, the son or daughter of an uncle or aunt.
Thou art, great lord, my father's sister's son, A cousin-german to great Priam's seed. — Shakespeare

The children of brothers and sisters are usually denominated first cousins, or cousins-german. In the second generation, they are called second cousins. See Cater-cousin, and Quater-cousin.

2.
A title formerly given by a king to a nobleman, particularly to those of the council. In English writs, etc., issued by the crown, it signifies any earl.
My noble lords and cousins, all, good morrow. — Shakespeare

Cousin , noun

Allied; akin. [Obsolete] — Chaucer