Merriam-Webster Collegiate Dictionary - extraneous

 adjective  Etymology: Latin extraneus — more at strange  Date: 1638  1. existing on or coming from the outside ~ light  2.  a. not forming an essential or vital part ~ ornamentation  b. having no relevance an ~ digression  3. being a number obtained in solving an equation that is not a solution of the equation ~ roots  Synonyms: see extrinsic  • ~ly adverb  • ~ness noun