PRAGUE, Okla. (NBC) – An Oklahoma high school valedictorian who was denied her diploma because she used the world “hell” in her commencement speech doesn’t plan to apologize for her choice of words, her father says.

David Nootbaar said he is furious that Prague High School is withholding his daughter Kaitlin's diploma because of her use of the word during the graduation speech in May. “She has worked so hard to stay at the top of her class and this is not right,” he said. “She earned that diploma. In four years she has never made a B. She got straight A’s and had a 4.0 the whole way through."

School officials declined to comment. "This matter is confidential and we cannot publicly say anything about it," Prague schools Superintendent Rick Martin said in a statement to KFOR-TV in Oklahoma City.