"It is logical for them to take precautions when dealing with unknown phenomena."

Their interest arises from a desire to study what appears to be an unknown or misunderstood phenomenon.

In the 1980s, homeschooling was still a relatively unknown phenomena.

Brief silence as the Guard closed on the unknown phenomena.

Anyway, as many a gossip writer could tell you, it was hardly an unknown phenomenon.

This is not an unknown phenomenon in the West.

A breakdown in cable TV service, hardly an unknown phenomenon, would do the same.

Were they somehow propelled through an unknown stellar phenomenon to end up at this point in time?

But fashion, a phenomenon unknown at the time, had a terrible impact on the garment industry.

He has come to Weltluna to investigate an unknown phenomenon.