English
Mondayitis
From Monday + -itis.
Formed from Monday + -itis
Proto-Indo-European *dʰegʷʰ- ‘to burn’
Proto-West Germanic *mānini dag
Old English mōnandæġ ‘day of the moon’
Middle English Monday
English Monday
The story
The term has been widely used in Australia for decades. Popularity of the term in the USA may be traceable to its use in the US comedy film Office Space (1999).
Today it means
noun The tired and apathetic feeling experienced by persons returning to work on a Monday after the weekend.
Language periods are conventional ranges, not dates for this word.
Etymograph / Mondayitis