unknown:1

adjective
un*known \ ˌən-ˈnōn \
before 12th century{ds||1|a|}
  • not known
  • not well-known
  • having an unknown value

unknown:2

noun
unknown \
14th century{ds||1|a|}
  • one that is not known or not well-known; especially : a person who is little known (as to the public)
  • a place, situation, or thing that is not known or understood
  • something that is not known or not yet discovered

Unknown Soldier

noun
Unknown Soldier \
1920
  • an unidentified soldier whose body is selected to receive national honors as a representative of all of the same nation who died in a war and especially in one of the world wars

unknown quantity

noun
unknown quantity \
  • someone or something whose abilities or characteristics are not yet known

unknown to

idiom
unknown to \
  • without being known about by (someone)

big unknown

noun
big unknown \
  • the important thing that everyone would like to know

of unknown origin

idiom
of unknown origin \
  • —used to say that the source or cause of something is not known
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