intrusion vs obtrusion

intrusion

noun
  • The forcible inclusion or entry of an external group or individual; the act of intruding. 

  • The insertion of a phoneme into the pronunciation of a word despite its absence from the spelling. (e.g. intrusive r) 

  • A structure that lies within a historic district but is nonhistoric and irrelevant to the district. 

  • Magma forced into other rock formations; the rock formed when such magma solidifies. 

obtrusion

noun
  • An interference or intrusion. 

  • An encroachment beyond proper limits. 

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