brotherhood

Concise Oxford English Dictionary © 2008 Oxford University Press:
brotherhood/ˈbrʌðəhʊd/

▶noun

• 1 the relationship between brothers.

  ■ a feeling of kinship and closeness.

• 2 an association or community of people with a common interest, religion, or trade.

  ■ N. Amer. a trade union.

– origin ME: prob. from obs. brotherred (based on OE -rǣden ‘condition, state’), assoc. with words ending in -hood and -head1.