a poem by an unknown author.
an obscure family.
an unknown amount.
an unknown island.
an unknown source.
an unknown writer.
an unnamed donor.
corporations responsible to nameless owners.
don't let anyone unknown into the house.
saw many strange faces in the crowd.
they came like angels out the unknown.
things obscurely felt surged up from unknown depths.
unsung heroes of the war.
used many strange words.