blood brother vs relative

blood brother

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

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

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

relative

noun
  • Someone in the same family; someone connected by blood, marriage, or adoption. 

  • A type of adjective that inflects like a relative clause, rather than a true adjective, in certain Bantu languages. 

adj
  • Expressed in relation to another item, rather than in complete form. 

  • Having the same key but differing in being major or minor. 

  • Connected to or depending on something else; comparative. 

  • Depending on an antecedent; comparative. 

  • Relevant; pertinent; related. 

  • Capable to be changed by other beings or circumstance; conditional. 

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