equivocal vs under cover

equivocal

noun
  • A word or expression capable of different meanings; an ambiguous term. 

adj
  • Having two or more equally applicable meanings; capable of double or multiple interpretation. 

  • Capable of being ascribed to different motives, or of signifying opposite feelings, purposes, or characters; deserving to be suspected. 

  • Uncertain, as an indication or sign. 

under cover

adj
  • protected by a covering or shelter 

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