Musty and Unoriginal

Musty adjective - Used or heard so often as to be dull.

Unoriginal and musty are semantically related In some cases you can use "Unoriginal" instead an adjective "Musty".

Unoriginal adjective - Using or marked by the use of something else as a basis or model.

Musty and unoriginal are semantically related in not original topic. Sometimes you can use "Musty" instead an adjective "Unoriginal".