Definition of "Extraneous" :

adjective: coming from the outside

"Extraneous light in the camera spoiled the photograph."

adjective: not essential

"The ballet struck me as extraneous and somewhat out of keeping with the rest of the play."

adjective: not pertinent to the matter under consideration

"An issue extraneous to the debate."

adjective: not belonging to that in which it is contained; introduced from an outside source

"Water free of extraneous matter."