IPA: //ʌnˈbɪdən//
KK: /ʌnˈbɪdən/
Describing something that occurs without being invited or requested, often referring to thoughts or actions that come to mind unexpectedly.
The memories of her childhood came back unbidden, filling her with nostalgia.
Unbidden → It is formed from "un-" (meaning not) and "bidden" (from Old English "biddan", meaning to ask or request). The word "unbidden" means not asked for or requested, indicating something that occurs without invitation or prompting.
Think of something that happens 'not' ('un-') 'asked for' ('bidden') — that's why unbidden means something that comes without being requested.