(US) A tendency of seniors in high school or college to skip class or otherwise slack off due to a desire to move on, or because they have already been accepted by a college and their further academic performance is no longer as relevant.
1984, W. Dean Memering, Frank O'Hare, The Writer's Work: Guide to Effective Composition - Page 121I don't know, but "senioritis" is real, as I discovered in my senior year. Senioritis is a frame of mind particular to high-school seniors. ...
2007, Vault Editors, The College Buzz Book - Page 336I worked hard my senior year, something that was particularly difficult due to the senioritis that many others were feeling. But it paid off!
