Definitions of antediluvian:

• noun:   a very old (or old fashioned) person
• noun:   any of the early patriarchs who lived prior to the Deluge
• adjective:   so extremely old as seeming to belong to an earlier period

  Example: "A ramshackle antediluvian tenement"

• adjective:   of or relating to the period before the Biblical flood

  Example: "Antediluvian man"