A male cousin who is more like a brother. Brosins and cuzisters grew up together supporting one another through thick and thin. They understand the crazy family they were born into, they share inside jokes, they are there for each other and they choose to hang out with one another because they want to. They are strong, goodhearted with an unbreakable bond, after all, they get it from their mamas.
My brosin and I are cousins by blood and siblings by choice.
by jbella314 April 15, 2017
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A half-brother who is also your cousin. The male offspring resulting when your sperm donor also impregnated your mom's sister. The male version of a couster.
I used to get along really well with my cousin Jake, until I found out we had the same dad. Now he's my brosin, and it's kinda awkward.
by Bructus August 16, 2010
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Your male cousin that was adopted in by your parents or your uncle and aunt adopted you.
by 459395 April 3, 2023
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Shopping/browsing with your bros but no homo.
Scott: Dude thats a sick sweatshirt. Is that new?
Taylor: Yeah, I got it this weekend when me and Luke were brosin' at the mall.
by thowe January 6, 2010
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A friend or family member who maintains the highest standards by hooking up and having children with two members of the same family.
Jane Doe hooked up with John Doe, had a son..then hooked up with John Doe's brother and had another son..therefore the kids are not only brothers they are also cousins.

Brothers+Cousins = Brosins
Brosins - pronounced Brah-sins
by RUkiddin'me August 3, 2011
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