Christian name vs surname

Christian name

noun
  • An English given name, particularly for ethnic Chinese who usually have a separate Chinese name. 

  • Any forename. 

  • A first name formally given to a child at a Christian baptism. 

surname

noun
  • The name a person shares with other members of that person's family, distinguished from that person's given name or names; a family name. 

  • The cognomen of Roman names. 

verb
  • To call by a surname. 

  • To give a surname to. 

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