Synonyms for Unexpected:

adj.

sudden (adjective)
immediate, instantaneous, hasty, abrupt, quick, sudden, precipitous.
surprising (adjective)
astounding, instantaneous, electrifying, unheralded, shocking, sudden, accidental, unlooked-for, stunning, startling, prodigious, abrupt, astonishing, unforeseen, fortuitous, amazing, wonderful, unanticipated, eye-opening, unpredicted, not in the cards, surprising, not bargained for, staggering, out of the blue.

adv

unpredicted (adverb)
out of the blue.

n.

coming without previous intimation, wonderful, eye-opening, fortuitous, phenomenal, remarkable, accidental, sensational, not bargained for, amazing, coming unaware, not on the books, staggering, stunning, unprepared for, electrifying, past conjecture, earth-shattering, extraordinary, like a bolt from the blue, Uncontemplated, not in the cards, prodigious. unexpected (noun)
forced, unheralded, unthought, unprovided for, unplanned, unlooked-for, unpredicted, unforeseen, sudden, unthought-of, out of the blue, unhoped-for, unscheduled, upset, unhoped, unannounced, unsuspected, unanticipated.

Other synonyms:

earth-shattering, phenomenal, remarkable, accidental, staggering. stunning, extraordinary. amazing. Other relevant words:
unannounced, stunning, unhoped-for, remarkable, unthought-of, forced, unsuspected, unprepared for, electrifying, prodigious, staggering, unhoped, fortuitous, unpredicted, out of the blue, not bargained for, amazing, unscheduled, unplanned, unheralded, unprovided for, earth-shattering, extraordinary, upset, phenomenal, unlooked-for, accidental, eye-opening, Uncontemplated, not in the cards, unthought, sensational, wonderful.

Usage examples for unexpected

  1. This was indeed an unexpected and bitter disappointment. – Won from the Waves by W.H.G. Kingston
  2. " I was visitin' my sister up in Hornville when he come back unexpected like. – Green Fancy by George Barr McCutcheon
  3. Molly and Mother Morrison were used to having unexpected guests, and no matter how many there were, in some mysterious manner plenty of good things to eat appeared on the table. – Brother and Sister by Josephine Lawrence