She is your great-Aunt
Your relation to your mums uncle is GREAT uncle. You're welcome! 
There is no relation between you and your grandmother's cousin-in-law's grandson.
Your grandmother's brother is your great uncle.
Your uncle is your daughters great uncle.
Your mother's uncle is your great uncle.
your grandfather in-law
If she's not your mother, that would make her your Aunt.
Grandmother and granddaughter relation
If you have no siblings but your daughter has an uncle, he is the brother of your spouse, your brother-in-law.
Your grandmother's great nieces are your second cousins.
Two people whose great grandmothers were sisters are third cousins to each other.
grand uncle or great uncle
You grandson is great great nephew to your uncle. You uncle is great great uncle to your grandson
You are not related as you do not share a common ancestor.
Second cousins once removed.
Your uncle is your children's great uncle and they are his great nieces and great nephews.
no he is my uncle I think I would know he was my grandmothers brother Judy M.Osbourne
Yes, he is their great uncle.
Your grandfather's brother is your great uncle and your parent's uncle.
He would be his great great great uncle
Your great uncle! (no blood relation there, but still your uncle:)
The word 'great' is used to indicate an additional generation. If your mothers brother is your Uncle, your grandmothers brother would be your great uncle. Your grandfathers father would be your great grandfather.
Blood relation equals incest, law relation equals strange. Either way it's taboo and your gonna have to accept that if you "love" your uncle.
His father's brother, as in his uncle.