helping verb vs modal

helping verb

noun
  • An auxiliary verb; a verb that accompanies the main verb in a clause. 

modal

adj
  • Relating to the statistical mode. 

  • Having separate modes in which user input has different effects. 

  • Requiring immediate user interaction and thus presented so that it cannot be closed or interacted behind until a decision is made. 

  • Of, or relating to a mode or modus. 

  • Of, relating to, or composed in the musical modi by which an octave is divided, associated with emotional moods in Ancient — and in medieval ecclesiastical — music. 

  • Of, or relating to the modality between propositions. 

  • Relating to the form of a thing rather to any of its attributes. 

  • Of, relating to, or describing the mood of a clause. 

  • a modal dialog; a modal window 

noun
  • A modal window, one that cannot be closed until a decision is made. 

  • A modal proposition. 

  • A modal verb. 

  • A modal form, notably a modal auxiliary. 

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