512. Was Lot Abraham's brother or nephew?

Lot was Abraham's brother.

And when Abram heard that his brother [Lot] was taken captive.... Genesis 14:14

And also brought again his brother Lot.... Genesis 14:16

Lot was Abraham's nephew.

Now these are the generations of Terah: Terah begat Abram, Nahor, and Haran; and Haran begat Lot. Gen.11:27

And Abram took Sarai his wife, and Lot his brother's son.... Genesis 12:5

And they took Lot, Abram's brother's son, who dwelt in Sodom, and his goods, and departed. Genesis 14:12