frequentative vs imperfective

frequentative

noun
  • Any of a subclass of imperfective verbs that denote a repeated action, no longer productive in English, but found in e.g. Finnish, Latin, Russian, and Turkish. 

adj
  • Serving to express repetition of an action. 

imperfective

noun
  • The imperfective aspect; a verb having this aspect. 

adj
  • Of, relating to or having the properties of the imperfective aspect. 

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