Blue-sky and Ivory-tower

Blue-sky adjective - Without immediate commercial value.

Ivory-tower and blue-sky are semantically related. In some cases you can use "Ivory-tower" instead an adjective phrase "Blue-sky".

Ivory-tower adjective - Very learned or educated but inexperienced in practical matters.

Blue-sky and ivory-tower are semantically related. Sometimes you can use "Blue-sky" instead an adjective phrase "Ivory-tower".