IPA: /prəˈvɜːbɪəli/
KK: /prəˈvɜrbɪəli/
In a way that relates to or resembles a saying that expresses a general truth or piece of advice.
She was proverbially late, always arriving after everyone else had started.
Proverbially → It is formed from "proverb" (from Latin *proverbium*, meaning a saying or a maxim) and "-ially" (a suffix meaning in a manner relating to). The word "proverbially" means in a manner that relates to or is characteristic of a proverb.
Think of a 'saying' ('proverb') that is expressed 'in a manner' ('-ially') — that's how you remember that 'proverbially' means in the way of a saying.