WordWeb Online

1. So extremely old as seeming to belong to an earlier period
   "a ramshackle antediluvian tenement"; "antediluvian ideas";
   - antiquated, archaic
    
2. Of or relating to the period before the biblical flood
   "antediluvian man";
   - antediluvial

1. Any of the early patriarchs who lived prior to the Noachian deluge
   - antediluvian patriarch
    
2. A very old person
   - ancient

Derived forms: antediluvians

See also: old

Type of: golden ager [N. Amer, informal], old person, oldster [N. Amer, informal], patriarch, senior citizen

Encyclopedia: Antediluvian