unknown (or strange, foreign or alien) adj. unkenned

I call [lexicography, as in defining words for a dictionary] a “craft” and not an “art”….  “Art conjures an image of the lexicographer as medium or conduit—a live wire that simply transmits something unkenned, alien. But “craft” implies care, repetitive work, apprenticeship and practice. (Kory Stamper, Word by Word, Pantheon [2017], p. 256.)

This word, when used in the above sense, can also be a synonym for strange, unfamiliar and unidentified.