un ‧ i ‧ ma ‧ gin ‧ a ‧ ble /ˌʌnɪˈmædʒənəb ə l◂, ˌʌnɪˈmædʒɪnəb ə l◂/ BrE AmE adjective
[ Word Family: adjective : ↑ imaginable ≠ ↑ unimaginable , ↑ imaginary , ↑ imaginative ≠ ↑ unimaginative , ↑ unimagined ; noun : ↑ imagination , ↑ imaginings ; adverb : ↑ unimaginably , ↑ imaginatively ; verb : ↑ imagine ]
not possible to imagine:
unimaginable wealth
—unimaginably adverb