You and your first cousins share the same Grandmother.
Your great-grandmother's sister's grandson is your second cousin once removed.
The grandmother, the grandmother's cousin, and your mother are of the same generation (first cousins). You are of the next generation and second cousin to the someone's parent. You and the someone are second cousins once removed.
Your mother's mother is your grandmother.Your grandmother's brother is your great uncle.Your great uncle's daughter is your mother's first cousin, and your first cousin, once removed.
Oh, dude, your great-grandmother's first cousin is like... your first cousin thrice removed. Yeah, it's like they're kind of related to you, but like, super distant, you know? So, like, you might not even know they exist until you do one of those intense family tree projects for school or something.
Your grandmother's sister is your great aunt. Her son is your parent's first cousin and your first cousin, once removed.
Your grandmother's first cousin's grandson is your third cousin.
Your grandmother's first cousin is your first cousin twice removed. Your grandmother's second cousin is your second cousin twice removed. And so forth.
Your third cousin.
Your great grandmother's first cousin's grandson is your third cousin once removed
The children of your grandmother's first cousin are your second cousins, once removed.
The first cousin of your great great great grandmother is your first cousin, five times removed.
Your grandmother's nephew is first cousin to one of your parents, and is therefore your first cousin once removed.
The grandchild of your great aunt is your second cousin.
The grandson of your great grandmother's brother is second cousin to one of your parents, and your second cousin once removed.
Your great grandmother's brother's great grandson is your third cousin.
Your Grandmother's sister is your great aunt. Her grand daughter is your second cousin and her great granddaughter is your second cousin, once removed.
Your grandmother's first cousin is your first cousin, twice removed. Your grandmother's second cousin is your second cousin, twice removed.