IPA: /dɪˈfeɪmər/
KK: /dɪˈfeɪmər/
A person who speaks badly about someone else, damaging their reputation.
The journalist was accused of being a defamer after publishing false information about the celebrity.
Defamer → It is formed from "de-" (meaning down or away) and "fama" (from Latin, meaning fame or reputation). The word "defamer" refers to someone who speaks down about another's reputation, thereby damaging it.
Think of someone who speaks 'down' ('de-') about another's 'fame' ('fama') — that's why a defamer is someone who harms another's reputation.