What Is a Niece's Son Called
A niece's son is typically called a grandnephew. In formal English, the same person may also be referred to as a great-nephew. Both terms describe the son of your niece or nephew.
How the Relationship Works
Your niece is the daughter of your brother or sister. Her son is therefore one generation below your sibling's line. In standard kinship charts, this places him as a grandnephew or great-nephew, depending on the style guide you follow.
Usage and Examples
In everyday conversation, many families simply say "grandnephew." Legal documents, family trees, and genealogy records often use "grandnephew" or "great-nephew" interchangeably. For more on family relationship terms, see the Kinship section at Merriam-Webster.
