"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 not known
"an unknown amount"
"an unknown island"
"an unknown writer"
"an unknown source" being or having an unknown or unnamed source
"a poem by an unknown author"
"corporations responsible to nameless owners"
"an unnamed donor" not known to exist
"things obscurely felt surged up from unknown depths" not famous or acclaimed