The adjective extraneous means something that is not directly connected or related to a matter being considered.
Synonyms are additional, irrelevant, nonessential, or unnecessary.
The word origins from Latin (1630s) extraneous meaning “external, strange”, literally meaning “that is without, from without”. It comes from extra meaning “outside of” plus -eous.
Someone added extraneous substances to our water.
Stop asking extraneous questions to our guests.
She must not be distracted by extraneous issues they said.