un‧dreamed-of /ʌnˈdriːmd- ɒv $ -ɑːv/ (
also un‧dreamt-of /ʌnˈdremt-/)
adjective much more or much better than you thought was possible:
undreamt-of success Men were becoming interested in fashion on a scale undreamed-of in the 1960s. [TahlilGaran] Dictionary of Contemporary English ▲