relative vs sibling

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. 

sibling

noun
  • A person who shares a parent; one's brother or sister who one shares a parent with. 

  • A node in a data structure that shares its parent with another node. 

  • The most closely related species, or one of several most closely related species when none can be determined to be more closely related. 

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