unseen

1. ADJ If you describe something as unseen, you mean that it has not been seen for a long time. 久未見過的

...a spectacular ballroom, unseen by the public for over 30 years. …公眾三十多年未見過的一個豪華舞廳。

2. ADJ You can use unseen to describe things which people cannot see. 看不見的[ADJ n, ADJ after v]

For me, a performance is in front of a microphone, over the radio, to an unseen audience. 對我來說,表演就是在麥克風前，通過無線電，傳播給看不見的聽眾。