observant vs penetrative

observant

adj
  • Alert and paying close attention; watchful. 

  • Diligently attentive in observing a law, custom, duty or principle; regardful; mindful. 

penetrative

adj
  • Displaying insight or discrimination; acute; penetrating. 

  • That can or does physically penetrate something; piercing, penetrating. 

  • That can penetrate opposition defences. 

  • Pertaining to sexual activity involving penetration by the penis. 

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