Source : Webster's Revised Unabridged Dictionary (1913)

Brotherhood \Broth"er*hood\, n. [Brother + -hood.]
   1. The state of being brothers or a brother.

   2. An association for any purpose, as a society of monks; a
      fraternity.

   3. The whole body of persons engaged in the same business, --
      especially those of the same profession; as, the legal or
      medical brotherhood.

   4. Persons, and, poetically, things, of a like kind.

            A brotherhood of venerable trees.     --Wordsworth.

   Syn: Fraternity; association; fellowship; sodality.

Source : WordNet®

brotherhood
     n 1: the kinship relation between a male offspring and the
          siblings
     2: people engaged in a particular occupation; "the medical
        fraternity" [syn: {fraternity}, {sodality}]
     3: the feeling that men should treat one another like brothers
     4: an organization of employees formed to bargain with the
        employer; "you have to join the union in order to get a
        job" [syn: {union}, {labor union}, {trade union}, {trades
        union}]