IPA: /kəˈlʌm.ni.əs.li/
KK: /kælˈʌm.ni.əs.li/
In a way that spreads false information about someone to damage their reputation.
She spoke calumniously about her rival, trying to ruin his chances of winning the election.
Calumniously → It is formed from "calumnia" (from Latin, meaning false accusation or slander) and the suffix "-ously" (meaning in a manner of). The word "calumniously" means in a manner that involves making false accusations or slander.
Think of 'calumnia' as relating to false accusations, and remember that 'calumniously' describes doing something in a slanderous way.