cousins

[LinL]

What relationship is someone to me who's great grandmother was my great grandfather's sister?

[sigma]

3rd cousins

[LinL]

Thanks for that. I get confused with the second cousins, cousins once removed etc...

[Aquagility]

Count the number of generations back to your common ancestor - in this case three.
Then if there is any difference in the generations between you and your cousin, this will be once, twice removed, etc.