An amazing person who is nice and honest and will always be faithful in relationships. A guy to hang out with and will make you laugh till you puke. A guy every girl wants to fuck and has a big penis. He is so awesome he doesn't have to compensate by being mean or working out. A good friend to have for cheating in school and doing crazy shit.
The act of maintaining a bro-like persona via the intake of sunlight.* This can be witnessed on Beaches and college campuses across the United states. (note: also possible around fires, at Dave Matthews concerts, etc.) Specifically occurs with men ages 18-24, "chill" (see chill) outside in small groups, or "crews". (note: sunglasses, vintage tees, sandals, and Abercrombie and Fitch paraphenalia are key indicators of brotosynthesis.) Common, less scientific, synonyms include but are not limited to the following: chillin', hangin, livin' the dream.
verb: brotosynthesize
*Recent studies indicate that the intake of cheap beer may aid in this process; it has not yet been confirmed.