Some supporters have posted “I don’t call someone Kalar” across their profile pictures.
The campaign has also attracted a wave of largely indignant reaction, with thousands of comments, many laden with obscenities against the activists.
They stand accused of stirring up racial hatred and seeking self-publicity.
“What should we call the Kalar if we don’t use the word Kalar?” challenged Nay Lin, while another Facebook user asked if they want “what is happening in the US” to happen in Myanmar.
Aung Aung, who did not want to give his real name for fear of repercussions, says he has been taunted with the term since he was a child.
“It still makes me angry,” the 26-year-old Hindu told AFP, adding he doesn’t dare get involved in the debate.
Activist Zay Linn Mon knows the word will not disappear overnight, but says the awareness campaign is a start.
“When we say we don’t like it, respect that and don’t use it.”