unprecedented

• POS: Adjective
• HYPHEN: un=prec=e=dent=ed

CIDE DICTIONARY

unprecedented, a. 

 Having no precedent or example; not preceded by a like case; not having the authority of prior example; novel; new; unexampled.  [1913 Webster]

OXFORD DICTIONARY

unprecedented, adj.
1 having no precedent; unparalleled.
2 novel.

Derivative

unprecedentedly adv.

THESAURUS

unprecedented

beguiling, bewildering, enigmatic, exceptional, extraordinary, fabulous, fantastic, fascinating, incomprehensible, inconceivable, incredible, indescribable, ineffable, legendary, marvelous, miraculous, mythical, noteworthy, outlandish, passing strange, phenomenal, portentous, primary, prodigious, prototypal, puzzling, rare, remarkable, sensational, strange, striking, stupefying, stupendous, uncopied, unduplicated, unexampled, unheard-of, unimaginable, unimitated, unique, unparalleled, unreproduced, unspeakable, wonderful, wondrous

ROGET THESAURUS

unprecedented

Dissimilarity

N dissimilarity, dissimilaritude, unlikeness, diversity, disparity, dissemblance, divergence, variation, difference, novelty, originality, creativeness, oogamy, dissimilar, unlike, disparate, divergent, of a different kind, unmatched, unique, new, novel, unprecedented, original, nothing of the kind, no such thing, quite another thing, far from it, cast in a different mold, tertium quid, as like a dock as a daisy, very like a whale, as different as chalk from cheese, as different as Macedon and Monmouth, lucus a non lucendo, diversified, otherwise, diis aliter visum, no more like my father than I to Hercules.

Unconformity

N unconformity, nonconformity, unconformity, disconformity, unconventionality, informality, abnormity, abnormality, anomaly, anomalousness, exception, peculiarity, infraction of law, breach, of law, violation of law, violation of custom, violation of usage, infringement of law, infringement of custom, infringement of usage, teratism, eccentricity, bizarrerie, oddity, je ne sais quoi, monster, monstrosity, rarity, freak, freak of Nature, weirdo, mutant, rouser, snorter, individuality, idiosyncrasy, originality, mannerism, aberration, irregularity, variety, singularity, exemption, salvo, nonconformist, nondescript, character, original, nonesuch, nonsuch, monster, prodigy, wonder, miracle, curiosity, flying fish, black sheep, black swan, lusus naturae, rara avis, queer fish, mongrel, random breed, half-caste, half-blood, half-breed, metis, crossbreed, hybrid, mule, hinny, mulatto, tertium quid, hermaphrodite, phoenix, chimera, hydra, sphinx, minotaur, griffin, griffon, centaur, saggittary, kraken, cockatrice, wyvern, roc, dragon, sea serpent, mermaid, merman, merfolk, unicorn, Cyclops, men whose heads do grow beneath their shoulders, teratology, fish out of water, neither one thing nor another, neither fish nor fowl, neither fish flesh nor fowl nor good red herring, one in a million, one in a way, one in a thousand, outcast, outlaw, off the beaten track, oasis, uncomformable, exceptional, abnormal, abnormous, anomalous, anomalistic, out of order, out of place, out of keeping, out of tune, out of one's element, irregular, arbitrary, teratogenic, lawless, informal, aberrant, stray, wandering, wanton, peculiar, exclusive, unnatural, eccentric, egregious, out of the beaten track, off the beaten track, out of the common, out of the common run, beyond the pale of, out of the pale of, misplaced, funny, unusual, unaccustomed, uncustomary, unwonted, uncommon, rare, curious, odd, extraordinary, out of the ordinary, strange, monstrous, wonderful, unexpected, unaccountable, outre, out of the way, remarkable, noteworthy, queer, quaint, nondescript, none such, sui generis, unfashionable, fantastic, grotesque, bizarre, outlandish, exotic, tombe des nues, preternatural, denaturalized, heterogeneous, heteroclite, amorphous, mongrel, amphibious, epicene, half blood, hybrid, androgynous, androgynal, asymmetric, adelomorphous, bisexual, hermaphrodite, monoclinous, qualified, singular, unique, one-of-a-kind, newfangled, novel, non-classical, original, unconventional, unheard of, unfamiliar, undescribed, unprecedented, unparalleled, unexampled, unconformably, except, unless, save barring, beside, without, save and except, let alone, however, yet, but, once in a blue moon, once in a million years, Int, what on earth!, what in the world!, What the devil!, Holy cow!, Can you top that?, Sacre bleu, never was seen the like, never was heard the like, never was known the like, I could hardly believe it, I saw it, but I didn't believe it.

Infrequency

N infrequency, rareness, rarity, fewness, seldomness, uncommonness, unfrequent, infrequent, rare, rare as a blue diamond, few, scarce, almost unheard of, unprecedented, which has not occurred within the memory of the ol, not within one's previous experience, not since Adam, scarce as hen's teeth, one in a million, few and far between, seldom, rarely, scarcely, hardly, not often, not much, infrequently, unfrequently, unoften, scarcely, scarcely ever, hardly ever, once in a blue moon, once, once in a blue moon, once in a million years, once for all, once in a way, pro hac vice, ein mal kein mal.