blood brother vs uncle

blood brother

noun
  • A brother by blood: a brother-german or half-brother, as distinguished from step-brothers. 

  • An unrelated male considered to share such a strong relationship generally. 

  • An unrelated male considered to share a brother-like relationship established by a ceremonial sharing of blood in some cultures. 

uncle

noun
  • The brother or brother-in-law of one’s parent. 

  • A source of advice, encouragement, or help. 

  • Used as a fictive kinship title for a close male friend of one's parent or parents. 

  • The male cousin of one’s parent. 

  • Used as a title for the male companion to one's (usually unmarried) parent. 

  • An affectionate term for a man of an older generation than oneself, especially a friend of one's parents, by means of fictive kin. 

  • Any middle-aged or elderly man older than the speaker and/or listener. 

intj
  • A cry used to indicate surrender. 

verb
  • To act like, or as, an uncle. 

  • To address somebody by the term uncle. 

How often have the words blood brother and uncle occurred in a corpus of books? (source: Google Ngram Viewer )