family name vs incognito

family name

noun
  • A given name common in a family, or already borne by someone in the family (in the context of naming someone in the family after that family member). 

  • A surname. 

incognito

noun
  • One unknown or in disguise, or under an assumed character or name. 

  • The assumption of disguise or of a feigned character; the state of being in disguise or not recognized. 

adv
  • Without revealing one's identity. 

adj
  • Without being known; in an assumed character, or under an assumed title; in disguise. 

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