The Collaborative International Dictionary of English v.0.48:

antediluvian \an`te*di*lu"vi*an\
   ([a^]n`t[-e]*d[i^]*l[=u]"v[i^]*an), a.
   Of or relating to the period before the Deluge in Noah's
   time; hence, antiquated; as, an antediluvian vehicle. -- n.
   One who lived before the Deluge.
   [1913 Webster]

WordNet (r) 3.0 (2006):

antediluvian
    adj 1: of or relating to the period before the biblical flood;
           "antediluvian man" [syn: antediluvian, antediluvial]
    2: so extremely old as seeming to belong to an earlier period;
       "a ramshackle antediluvian tenement"; "antediluvian ideas";
       "archaic laws" [syn: antediluvian, antiquated, archaic]
    n 1: any of the early patriarchs who lived prior to the Noachian
         deluge [syn: antediluvian, antediluvian patriarch]
    2: a very old person [syn: ancient, antediluvian]

Moby Thesaurus II by Grady Ward, 1.0:

98 Moby Thesaurus words for "antediluvian":
   Bronze Age man, Gothic, Hominidae, Iron Age man, Methuselah,
   Stone Age man, Victorian, aboriginal, aborigine, age-old, aged,
   ancient, ante-bellum, antemundane, anthropoid, antiquated, antique,
   ape-man, archaic, autochthon, back number, before the Fall,
   before the Flood, before the war, bushman, cave dweller, caveman,
   classical, conservative, dad, dodo, elder, fogy, fossil,
   fossil man, fossilized, fud, fuddy-duddy, granny, grown old,
   has-been, hoary, hominid, humanoid, longhair, man of old,
   matriarch, medieval, mid-Victorian, missing link, mossback,
   of other times, old, old believer, old crock, old dodo, old fogy,
   old liner, old man, old poop, old woman, old-timer, old-world,
   patriarch, petrified, pop, pops, pre-Aryan, pre-Christian,
   pre-Renaissance, pre-Roman, preadamite, preclassical, precultural,
   prehistoric, prehistoric man, prehuman, prelapsarian,
   premillenarian, premundane, prerevolutionary, preromantic, prewar,
   primate, primitive, protohistoric, protohuman, reactionary,
   regular old fogy, relic, square, starets, stick-in-the-mud,
   superannuated, timeworn, traditionalist, troglodyte, venerable