Huh. How do you handle a student who uses a racial slur in their history paper? For reasons of confidentiality I can't go into the details, but I believe this student used the word out of ignorance. Still. It is common sense to avoid using a word in a paper if you don't know its meaning. My other thought is that she might have quoted an historical figure and didn't cite the source--in sum, she plagiarized. What's worse?
I have asked this student to call me but haven't heard back from her. The disadvantage to teaching online is that you are at the student's mercy to respond to your requests for communication.