Ace and Rad

Ace adjective - Having or showing exceptional knowledge, experience, or skill in a field of endeavor.

Rad and ace are semantically related in great topic. In some cases you can use "Rad" instead an adjective "Ace".

Rad noun - A unit of absorbed ionizing radiation equal to 100 ergs per gram of irradiated material.

Ace and rad are semantically related in good topic. Sometimes you can use "Ace" instead an adjective "Rad", if it concerns topics such as pleasant.