Synonyms for Senior citizen:

• adj.

  •aged (adjective)
  • over the hill,
  • timeworn,
  • ageold,
  • been around,
  • senescent,
  • creakier,
  • worse for wear,
  • creaky,
  • oldie.

• n.

  •
  • centenarian,
  • ancient,
  • the aged,
  • the elderly,
  • octogenarian,
  • youth,
  • the old,
  • methuselah,
  • nonagenarian.
  •elder (noun)
  • fore bearers,
  • fore bearer,
  • oldests,
  • fore-bearer,
  • fore-bearers,
  • old fogeys.
  •golden ager (noun)
  • goldenager.
  •senior (noun)
  • first-borns,
  • old timer,
  • grand fathers,
  • grand mother,
  • grand-father,
  • firstborns,
  • retired people,
  • elderly people,
  • elderly persons,
  • old folks,
  • first borns,
  • grand mothers,
  • first born,
  • grand-mothers,
  • retired persons,
  • grand-fathers,
  • goldenagers,
  • doyennes.
  •senior citizen (noun)
  • old person.
  •someone of advanced years (noun)
  • patriarch,
  • geriatric,
  • retiree,
  • old-age pensioner.

• Other synonyms:

  •
  • old-timer.