'Centenarian' definitions:

Definition of 'centenarian'

From: WordNet
adjective
Being at least 100 years old
noun
Someone who is at least 100 years old

Definition of 'Centenarian'

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