Definition of brother

What does the word brother mean?

• part of speech: noun

  (pl. brothers& in some senses brethren, see below). Son of same parents or (strictly half-b.) parent as another person (the latter usu. specified by my &c. or a possessive case; pl. abbr. Bros, in title of firm, as Smith Bros& Co.); close friend; fellow citizen, countryman, or man, equal, (a man& a b., esp. of negro slaves); fellow-member of religious society (pl. brethren); fellow-member of guild, order, profession, &c. (pl. brethren); official of certain companies &c. (Elder B., Brethren, of Trinity House); companion, associate, (pl. brothers) often with specification as b. in arms, of the angle; member of religious order (as title; either pl.); vocative of sovereigns to each other; b. german, on both sides, b. uterine, of same mother only; b.-in-law, b. of one\'s husband or wife, husband of one\'s sister. Hence brotherless a., brotherlike a. & adv., brotherly a. & adv., brotherliness n. [old English]