centenarian

from WordNet (r) 3.0 (2006)

centenarian
    adj 1: being at least 100 years old
    n 1: someone who is at least 100 years old

from The Collaborative International Dictionary of English v.0.48

Centenarian \Cen`te*na"ri*an\, a.
   Of or relating to a hundred years. -- n. A person a hundred
   years old.
   [1913 Webster]

from Moby Thesaurus II by Grady Ward, 1.0

66 Moby Thesaurus words for "centenarian":
      C, Father Time, Methuselah, Nestor, Old Paar, bicentenary,
      bicentennial, cental, centare, centenary, centennial, centennium,
      centigram, centimeter, centipede, centistere, centred, centref,
      centrev, centumvir, centumvirate, centurion, century, cwt, dotard,
      elder, gaffer, geezer, golden-ager, gramps, grandfather, grandsire,
      graybeard, gross, hecatomb, hundred, hundredweight, long hundred,
      nonagenarian, octogenarian, old chap, old codger, old dog,
      old duffer, old geezer, old gent, old gentleman, old man,
      old party, old-timer, older, oldster, one C, pantaloon, patriarch,
      presbyter, senior citizen, septuagenarian, sesquicentenary,
      sesquicentennial, sexagenarian, tercentenary, tercentennial,
      the quiet-voiced elders, venerable sir, veteran