The Oxford Thesaurus An A-Z Dictionary of Synonyms - unheard-ofadj.

1) unknown, unfamiliar, obscure, unidentified, nameless, unsung: She is busy trying to promote some unheard-of sculptor. 2 unimaginable, undreamed of or undreamt of, unprecedented, unimagined, unbelievable, inconceivable, unusual: They took the unheard-of step of requiring that refunds be paid. Her starting salary is an unheard-of њ100,000. 3) shocking, offensive, outrageous, disgraceful, extreme, unthinkable, outlandish: The victims were subjected to unheard-of tortures.