Not conforming to accepted rules or standards.

Roget 83: 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 etc. 870; unexpected, unaccountable; outre [Fr.], out of the way, remarkable, noteworthy; queer, quaint, nondescript, none such, sui generis [Lat.]; unfashionable; fantastic, grotesque, bizarre; outlandish, exotic, tombe des nues [Fr.], preternatural; denaturalized^†.    heterogeneous, heteroclite [Gramm.], amorphous, mongrel, amphibious, epicene, half blood, hybrid; androgynous, androgynal^†; asymmetric etc. 243; adelomorphous^†, bisexual, hermaphrodite, monoclinous^†.    qualified etc. 469.    singular, unique, one-of-a-kind.    newfangled, novel, non-classical; original, unconventional, unheard of, unfamiliar; undescribed, unprecedented, unparalleled, unexampled.    ... show more

Not conventional or conformist.

Not conforming to legality, moral law, or social convention:
— An unconventional marriage.

synonyms: improper, unlawful.