Unfound and Unheard-of

Unheard-of and unfound are semantically related. In some cases you can use "Unheard-of" instead an adjective "Unfound".

Unheard-of adjective - Not known or experienced before.

Unfound and unheard-of are semantically related. You can use "Unfound" instead an adjective phrase "Unheard-of".