first cousin

first cousin (plural first cousins)

1. A child of a parent's sibling; a nephew or niece of a parent; a child of one's uncle or aunt.
2. A relative who has with the other person only two grandparents or one grandparent (maternal or paternal) in common, but parents are different.
3. (figurative, by extension) Anything closely related.
   • 1878, Connecticut Churchman, volume 37, page 246:

     […] that coarseness which is first cousin to sin.

   • 1920, Boys' Life, volume 10, number 4, page 22:

     [H]e was afraid the Mexicans, who were, he claimed, first cousin to the spigotties, would catch us off our guard and give us the same treatment.

• Starting with two first cousins (two persons with a common grandparent), the relationship between one of those persons and the offspring of the other is first cousin once removed.
• The relationship between one of those persons and the grandchild of the other is first cousin twice removed.
• The relationship between one of those persons and the great-grandchild of the other is first cousin thrice removed.

• cousin
• cousin-german
• full cousin

• double first cousin
• sesquiple first cousin

• “first cousin”, in OneLook Dictionary Search.