imperfect vs progressive tense

imperfect

noun
  • a tense of verbs used in describing a past action that is incomplete or continuous 

  • something having a minor flaw 

verb
  • to make imperfect 

adj
  • not perfect 

  • belonging to a tense of verbs used in describing a past action that is incomplete or continuous 

  • known or expected to be polyphyletic, as of a form taxon. 

  • unisexual: having either male (with stamens) or female (with pistil) flowers, but not with both. 

progressive tense

noun
  • Synonym of continuous tense. 

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