Behaviour characteristic of high school seniors, but can be contracted (it's like a disease) as early as middle school. Symptoms include rampant class-skipping and general apathy towards all things school-related. Example: I won't be doing my homework tonight either. Senioritis has got me bad this year.
SENIORITIS
Meaning of SENIORITIS in English
Slang English vocab. Английский сленговый словарь. 2012