According to the Korea Communications Standards Commission, the number of cases where it found offensive terms and requested the content be deleted or certain accounts shut down has risen from 622 in 2013 and 705 in 2014 to 833 this year.
The state watchdog said the terms build social prejudice against women, the elderly, the disabled and foreigners by encouraging people blindly to hate the subjects.
Many of the terms were sexually offensive to men and women. In one case, an online broadcaster used language belittling the disabled.
Expressions insulting the elderly included "if you are old you should die," or "why don't you wait to die locked up in your home."
The watchdog said it would continue to monitor certain cities that tended to produce many such terms.
The use of offensive language can be subject to criminal punishment on charges of defamation.