obverse vs relational

obverse

adj
  • Corresponding; complementary. 

  • Having the base, or end next to the attachment, narrower than the top. 

  • Turned or facing toward the observer. 

noun
  • A proposition obtained by obversion, e.g. All men are mortal => No man is immortal. 

  • The heads side of a coin, or the side of a medal or badge that has the principal design. 

relational

adj
  • Relating to relations. 

  • Friendly and peaceful. 

  • Dealing with the whole of human relations and their social context, rather than an independent and private space. 

  • Of a database technology using tables and the principles set forth by Dr. Edgar F. Codd. (Contrary to popular notion, "relation" in this context refers to tables, and not linkages.) 

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