IPA: /ɪkˈstreɪniəs/
KK: /ɛkˈstreɪniəs/
Something that is not essential or relevant to the subject being discussed; it comes from outside and does not belong to the main topic.
The report included extraneous details that distracted from the main argument.
Extraneous → It is formed from "extra-" (meaning outside) and "aneus" (from Latin, meaning pertaining to). The word "extraneous" refers to something that is outside or not essential to the matter at hand.
Think of something that is 'outside' ('extra-') and 'pertaining to' ('aneus') — that's why extraneous means something that is not essential or relevant.