Synonyms for Senior:

adj.

influential (adjective)
authoritative, important, commanding, motivational, leading, powerful, masterful, influential, supreme, controlling, prejudicial, ruling, predominant.
master (adjective)
principal, head, commanding, ruling, Presiding, star, master, directing, leading, governing.
old (adjective)
geriatric.
older or of higher rank (adjective)
chief, higher, leading, superior, more advanced.
superior (adjective)
champion, chosen, crowning, sovereign, supreme, furthermost, commanding, elite, choice, zenith, best, A 1, eminent, Headmost, ascendant, maximum, predominant, paramount, dominant, chief, uppermost, master, leading, furthest, king, signal, foremost, most, ruling, better, controlling, above, consummate, superior, quintessential.
veteran (adjective)
experienced, expert, patriarchal, veteran, master.

n.

below, born, common, B-list, genteel, good, A-list. age, the grey pound, the gray dollar, old age, decrepitude, ageing, advanced, new, sexagenarian. aging, ancient, decrepit, venerable, geriatric, higher, over. BMP, campus, auditor, COED, alumnus, Big Man on Campus, fresher, alum, dropout, alumna. the aged, oldster, octogenarian, the elderly, nonagenarian, the old, old folk, centenarian, pensioner, methuselah. elder (noun)
more advanced, next higher in rank, of greater dignity, next older, higher in rank, of advanced standing.
master (noun)
commander, captain, lord, headmaster, mandarin, proprietress, star, headmistress, executive, head, squire, officer, mahatma, titleholder, director, guru, abbot, commandant, quartermaster, dean, sire, proprietor, manager, maestro, landlady, mother, ruler, principal, kingpin, president, governor, landlord, authority, leader.
older person (noun)
ancient, head, old-timer, old folk, oldster, patriarch, pensioner.
senior citizen (noun)
pensioner.
undergraduate (noun)
COED.
veteran (noun)
old hand, old-timer, patriarch, gray-beard, old soldier.

Other synonyms:

the gray dollar, decrepitude, old age, the grey pound. decrepit, venerable, oldster. higher. age, advanced. ancient.

Usage examples for senior

  1. The Senior Second stood out for the Chief. – Love Stories by Mary Roberts Rinehart
  2. Some of the senior Fellows spoke of the time when dinner was at 2, and regretted the change. – Autobiography of Sir George Biddell Airy by George Biddell Airy