the kinship relation between a male offspring and the siblings
"After his father passed away, the three brothers felt an immediate sense of brotherhood as they supported each other through the funeral arrangements."
the feeling that men should treat one another like brothers
"The team's victory was celebrated not just as a win, but as a testament to their deep brotherhood on the field."
an organization of employees formed to bargain with the employer
"you have to join the union in order to get a job"
The state of being brothers or a brother.
"The ceremony marked the official moment when he was welcomed into their secret brotherhood, granting him the same status as all the men who had come before him."