ungrounded vs unprovoked

ungrounded

adj

  • Not grounded; without ground or basis, unreal, false. 

  • Not connected to ground potential 

unprovoked

adj

  • Happening without provocation or motivation. 

adv

  • Without provocation or motivation. 

  • He attacked me, suddenly, unprovoked. 

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