unknown
noun
an unknown and unexplored region
“they came like angels out the unknown”
anyone who does not belong in the environment in which they are found
a variable whose values are solutions of an equation
Synonymsunknown quantity
adjective
not known
“an unknown amount”
“an unknown island”
Oppositesknownbeing or having an unknown or unnamed source
“a poem by an unknown author”
“corporations responsible to nameless owners”
not known to exist
“things obscurely felt surged up from unknown depths”
not famous or acclaimed
“an obscure family”
“unsung heroes of the war”
not known before
“used many strange words”
“saw many strange faces in the crowd”
Synonymsstrange
Source: WordNet 3.1, Princeton University