Many times I come across the wrong usage â€œcousin brotherâ€ or â€œcousin sisterâ€. There are cousins and not â€œcousin brotherâ€ or â€œcousin sisterâ€. It is too bad when such usage appears on newspapers or TV channels.
Those who have same grandparents but different parents are first cousins. Those who have same great grandparents but different parents and grandparents are second cousins. So it goes on.
Many languages do not have the word for cousins.