unseen
adjective /ˌʌnˈsiːn/
  /ˌʌnˈsiːn/
Idioms - that cannot be seen; that is not seen
- unseen forces
 - He was killed by a single shot from an unseen soldier.
 - I had the strong sense of an unseen presence in the room.
 - I managed to slip out of the room unseen.
 
 - not previously seen
- unseen dangers
 - The exam consists of an essay and an unseen translation.
 
 
Idioms 
sight unseen 
- if you buy something sight unseen, you do not have an opportunity to see it before you buy it
- I bought it, sight unseen.