unseen

1. ADJ If you describe something as unseen, you mean that it has not been seen for a long time. 久未见过的

...a spectacular ballroom, unseen by the public for over 30 years. …公众三十多年未见过的一个豪华舞厅。

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

For me, a performance is in front of a microphone, over the radio, to an unseen audience. 对我来说,表演就是在麦克风前，通过无线电，传播给看不见的听众。