I. (ˈ)ek|strānēəs, ikˈs- adjective
Etymology: Latin extraneus — more at strange
1.
a. : existing or originating outside or beyond : external in origin : coming from the outside
extraneous light in a camera
protecting the contents of the container from extraneous moisture
no premiums or other extraneous inducements
b. : brought in, introduced, or added from an external source or point of origin
a valley bottom covered with extraneous soil
relying upon an extraneous income
2.
a. : not forming an essential or vital part : not belonging to something as a proper or natural part : not intrinsic : accidental , foreign
extraneous sounds
they considered art to be extraneous to reality
a ballet that struck me as extraneous and somewhat out of keeping with the rest of the play — Wolcott Gibbs
extraneous incidents in a novel
a building with extraneous ornamentation
b. : having little or no relevance : irrelevant : not pertinent
an unexpected and altogether extraneous remark
an extraneous digression
c. : having little or no interdependence or connection : unrelated
a series of extraneous books
extraneous events
Synonyms: see extrinsic
II. adjective
: being a number obtained in solving an equation that is not a solution of the equation
extraneous roots