Overemphasis is when people give something more importance than it deserves, or more than fits the situation. It is a noun, a little formal — the kind of word you meet in essays, news, and meetings. A school can have an overemphasis on tests; a report can show an overemphasis on one scary case. The over- here is not “above”; it is “too much of.” The complaint hiding in the word is that the extra weight is a mistake, not just a choice. Though actually, everyday talk often says the same thing with smaller words: too much emphasis on…, they make too much of….