IPA: /ɪkˈstreɪniəsli/
KK: /ɛkˈstrænɪəsli/
In a way that is not relevant or essential; something that is added but not necessary.
The report included extraneously detailed information that was not needed for the main argument.
Extraneously → It is formed from "extra-" (meaning outside or beyond) and "neus" (from Latin "aneus", meaning pertaining to or related to). The word "extraneously" means in a manner that is outside or unrelated to the main subject or matter.
Think of something that is 'outside' ('extra-') the main topic — that's why extraneously means something that is not directly related.