IPA: /ɪmˈpɛkəblɪ/
KK: /ɪmˈpɛkəblɪ/
In a way that is perfect and without any mistakes or flaws.
She dressed impeccably for the formal event.
Impeccably → It is formed from "im-" (meaning not) and "peccare" (meaning to sin or do wrong) combined with the suffix "-ably" (meaning in a manner). The word "impeccably" means in a manner that is without sin or fault, thus indicating perfection.
Think of 'not' ('im-') doing anything wrong ('peccare') — that's why doing something impeccably means doing it perfectly.