tricenarian in English dictionary tricenarian Meanings and definitions of "tricenarian" Between the ages of 30 and 39. In one's fourth decade. A person whose age is between thirty and thirty-nine years, inclusive; someone in his or her thirties. Someone in his or her fourth decade. adjective Between the ages of 30 and 39. In one's fourth decade. noun A person in their thirties, a person aged between 30 and 39 years (inclusive). a person between age thirty and thirty-nine more Grammar and declension of tricenarian tricenarian ( not comparable) tricenarian ( plural tricenarians) tricenarian (not comparable) tricenarian (plural tricenarians) more Sample sentences with "tricenarian" Declension Stem Try again Available translations Czech Finnish French Polish Portuguese Tagalog Authors