IPA: /dɪˈfaɪər/
KK: /dɪˈfaɪər/
A person who challenges or opposes something, especially authority or tradition.
She is a defier of conventional norms, always pushing for change.
Defier → It is formed from "defy" (from Old French *defier*, meaning to challenge or resist) and "-er" (meaning a person who). A defier is a person who challenges or resists authority or norms.
Think of someone who 'challenges' ('defy') and the '-er' just means a person. A defier is someone who stands up against something.