godmother vs godparent

godmother

noun
  • A woman present at the christening of a baby who promises to help raise the child in a Christian manner; a female godparent who sponsors the baptism of a child. 

verb
  • To act as godmother to. 

godparent

noun
  • A person who, at a child's naming ceremony or baptism, agrees to help raise the child, originally and especially in regard to their religious development. 

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