Your sister's uncle is also your uncle.
Your uncle's first cousin would be one of your grandparent's nieces or nephews, which makes them your first cousin once removed.
The fact that this uncle is the oldest of your uncles makes no difference to the relationship.
Your mothers sisters Granddaughter is your second cousin
Cousin. Your parents brothers and sisters are aunts and uncles. and the aunt and uncles children are your cousins.
Your uncles daughter would be your cousin.
Your aunts and uncles are the sisters and brothers of your parents. So they are "blood related." But you also call the husband of your mother's sister your uncle, and he is not "blood related." So aunts and uncles are not always really related to you.
your auntie.. your sisters father is your dad..your dads brother is your uncle..your uncles daughter is your cousin and your cousins mother is your auntie:)!
your uncles daughter would be your cousin
their parents, brothers, sisters, cousins, aunts, uncles, and people who are related to them.
Your aunts and uncles are the sisters and brothers of your parents.
your uncles daughter would be your cousin
Your uncle's nephew may be either a sibling or a cousin or yourself.
Your uncle's first cousin is also your parent's first cousin, and your first cousin, once removed - if your uncle is the brother of one of your parents. Sometimes your uncle is the husband of your parent's sister. Then his cousin in not related to you.
You are related to some of your cousin's cousins, and not to others. If you have an ancestor in common, you are related. If you do not can a common ancestor somewhere, then you are not related.