be of unknown origin

Of the country's 149 probable cases, only six are of unknown origin.

The current structure that exists is of unknown origin.

Beautiful and terrifying, the blaze is of unknown origin.

However, the approaching drone is of unknown origin and capabilities."

Technically a worm, the virus is of unknown origin and was spotted by computer security companies on May 22.

We found that 20 of the estimates originated from six source studies, with one being of unknown origin.

The name "burlap" appears to be of unknown origin.

The box in question is of unknown origins, though it carries a distinct Egyptian motif.

Other modifications, generally of a trivial nature, which are of unknown origin.

Both men are of unknown origin and have little recorded for them beside a few notes and their names.

The village's coat of arms is of unknown origin.

Both lyrics and melody is of unknown origin.

The public domain lyrics are of unknown origin.

The two overlapping types here are of unknown origin:

The unusual proportions of 13:15 are of unknown origin.

These flares are of unknown origin, but they are exceedingly violent events.

The word is of unknown origin, but was earliest used by British seamen in the 19th century.

Large paintings, both framed and mural, line the walls and are of unknown origin.

A common problem at the sites is that much of the pollution is of unknown origin.

It is of unknown origin, but perhaps comes from jug a familiar name used to describe "a low woman, a maidservant" in the same period.

They are of unknown origin but are believed to date from the Middle Ages.

Much of the poetry that is attributed to her is of unknown origin.

It is an old word in English, existing more than 1,000 years ago, but it is of unknown origin.

The wig found near the mummy is of unknown origin, and cannot be conclusively linked to that specific body.

They are of unknown origin; what little we have of their language suggests it is a language isolate.