Sonphew 

A nephew that you treat like a son because you’re NEVER having kids of your own.

I can’t wait to spoil and fill my sonphew up with sweets, then drop him off to his parents.

Sonphew by PhatBoi88 May 10, 2020

sonphew 

Male child produced by a lesbian couple using a duncle (see definitio of duncle on urbandictionary.com)

none yet

sonphew by Ollie and Alex January 20, 2004

sonphew 

When your son is the sister of your wife's son, because you had sex with her sister and she also had your your child (your son)

My sonphew and his sister are constantly fighting over what to watch on tv.

sonphew by Okthankunext November 29, 2024

Sonphew 

A son you are the father of because you had sex with your wife's sister, she got pregnant and you produced a child together. (Your sister-in-law's OTHER sons would be your nephews)

My sonphew is always arguing with his little sister over the television.

Sonphew by Okthankunext November 30, 2024

Sonephew 

Sonephew is son from a biological brother and sister. They have him.

Stranger: I found out that I’m a Sonephew

Sonephew by Sakurakage May 15, 2021