Synonyms for Elderly (same or very similar meaning)
WordNet sense 1 (people who are old collectively):
aged, agedWordNet sense 2 (advanced in years; (`aged' is pronounced as two syllables)):
senior, olderWordNet sense 3 ((used especially of persons) having lived for a relatively long time or attained a specific age):
oldFrom the ODE community, based on WordNetadd/edit