IPA: /ˌɪn.dɪɡˈneɪ.ʃən/
KK: /ɪnˈdɪɡneɪʃən/
A strong feeling of anger or annoyance caused by something that is unfair or wrong.
She expressed her indignation at the unfair treatment of her colleague.
Indignation is formed from "in-" (meaning not) and "dignus" (meaning worthy). The word conveys a sense of anger or annoyance at what is perceived as unfair treatment, suggesting that something is not worthy of respect or fairness.
Think of feeling 'not worthy' ('in-' means not and 'dignus' means worthy) when faced with unfairness — that's what indignation is all about.