clashing vs oppugnancy

clashing

noun
  • A clash; the sound or action of clashing; violent collision. 

adj
  • conflicting, contrasting, or contrary; inconsonant, incompatible, or irreconcilable 

  • mismatched, inharmonious, discordant or dissonant, not fitting well together (especially in regards to aesthetics, colors, clothing, or sounds) 

  • adverse or antagonistic; disagreeing or opposing 

  • Producing a clash or series of clashes. 

oppugnancy

noun
  • The act of oppugning; opposition; resistance 

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