In the English language, your sister's son is your nephew, regardless of whether your sister is older or younger than you are. All children of your siblings are either your nephew (if a boy) or a your niece (if a girl).
cousin
Alludu
Your father's brother's son is your first cousin and your daughter's second cousin.
Your Step-brother. If he isn't your brother but he is your father's son, he's you.
your
Your son will be a nephew to your brother, and will call him "Uncle".
the father, the elder brother,the servants.
your 5th cousin
The son of your brother is your "nephew".
The son of your brother is your "nephew".
cousin!
Your cousin.