Wikipedia is one of the few sources that tackles the definition of senioritis:
The main symptoms of senioritis include chronic procrastination, lack of motivation, a drop in academic performance, and “coasting,” which is the act of going through classes with very little concentration or application of intent. This usually happens in the last year of high school, college or graduate school. One of the most notable symptoms of senioritis, is that all attempts by educators to curb senioritis tend to actually increase senioritic symptoms. High school seniors experiencing senioritis after admittance to college are fed up with high school; as they see it, they have achieved high school’s goal of getting into college and don’t understand why they are still expected to work.
Halfway through the semester, many of my seniors are suffering from senioritis. The quality of their work is declining; they are counting the days until spring break and until graduation; a couple have been in In School Suspension; three are suspended; and several start nodding off each class period.
Today I delivered my annual Senioritis Speech and warned students that if they coast until graduation, they may discover that colleges that have already accepted them into the freshman class may indeed rescind that offer. I challenged them, “Read the fine print in that college acceptance letter and see what it says about ‘pending acceptance or review of final transcript.’”
I have good kids and I want them to enjoy the end of their high school careers; I just want them to hang in there a few more weeks and save the coasting until May. By then, we should have a little more time to play and celebrate their achievements.
As I spoke with the kids today, I told them about a parent who exploded at me about a decade ago when her daughter failed my class and did not graduate. The mother admitted that the student had been failing the entire semester and that I had phoned her to warn her that her daughter was in danger of failing. In the end when the child failed, however, the mother blamed me. When I asked why she thought it was my fault that her daughter had failed, she replied, “You were too nice to her. Since you were so sweet, she didn’t think you would actually fail her!”
I now make it a point to tell seniors, “I may love you and I may laugh with you, but if you don’t meet the requirements of the class, I will indeed fail you and keep you back with me another year where I will love you and laugh with you for another year!”
I think there is a special place in Heaven for teachers who work with high school seniors during the spring.