grand-uncle

/G R AE1 N D AH0 NG K AH0 L/
noun
  1. 1

    A brother of grandparent

noun
  1. 1

    An uncle of one's parent (i.e. a brother or brother-in-law of one's grandparent).

Source: https://en.wiktionary.org/wiki/grand-uncle, https://en.wiktionary.org/wiki/granduncle, https://en.wiktionary.org/wiki/great-uncle