IPA: /ɪˈrɛvərəns/
KK: /ɪˈrɛvərəns/
A behavior or comment that shows a lack of respect for something that is usually considered serious or important.
His irreverence during the ceremony surprised everyone.
Irreverence is formed from "ir-" (meaning not) and "reverentia" (from Latin, meaning respect or reverence). The word describes a lack of respect or a disregard for something that is usually respected or revered.
Think of 'not' ('ir-') showing 'respect' ('reverentia') — that's why irreverence means a lack of respect.