glib vs plain-speaking

glib

adj
  • Having a ready flow of words but lacking thought or understanding; superficial; shallow. 

  • Snarky or unserious in a disrespectful way. 

  • Artfully persuasive but insincere in nature; smooth-talking, honey-tongued, silver-tongued. 

verb
  • To make smooth or slippery. 

noun
  • A mass of matted hair worn down over the eyes, formerly used in Ireland. 

plain-speaking

adj
  • Synonym of plain-spoken 

How often have the words glib and plain-speaking occurred in a corpus of books? (source: Google Ngram Viewer )