opposing vs shielding

opposing

adj
  • That opposes or oppose; on the opposite side. 

shielding

noun
  • The situation, in NMR spectroscopy, in which a local magnetic field is weakened by the presence of neighbouring nuclei 

  • Action done by the person with the ball to protect the ball from the defender; the person concerned keeps his body between the ball and the defender. 

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