godsib vs knack

godsib

noun
  • One's sibling or kin via a godfamily tie: one's or one's child's godparent, or one's godchild's parent, or one's godparent's child. 

knack

noun
  • A petty contrivance; a toy. 

  • A readiness in performance; aptness at doing something. 

  • Something performed, or to be done, requiring aptness and dexterity. 

verb
  • To speak affectedly. 

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