sight unseen
adverb
1- without the opportunity to look at the object in question beforehand在事先没机会看实物的情况下：
they bought their computers sight unseen through the mail.
他们事先没有看到实物, 就发函购买这些电脑。
1.1
- without being seen没有被看见：
what other treasures remain sight unseen?
还有什么金银财宝没有被发现？