un·heard–of 
/ˌʌnˈhɚdˌʌv/ adjective
/ˌʌnˈhɚdˌʌv/ adjective : not known to have existed or happened before : very unusual
▪ In those days, indoor plumbing was almost unheard-of. [=very few people had indoor plumbing] ▪ He was hired for an unheard-of salary of more than a million dollars. ▪ It's not unheard-of for a patient's condition to improve this quickly.
▪ In those days, indoor plumbing was almost unheard-of. [=very few people had indoor plumbing] ▪ He was hired for an unheard-of salary of more than a million dollars. ▪ It's not unheard-of for a patient's condition to improve this quickly.
