BETTER LATE THAN NEVER….Last year I asked where the term “mouth breather” as a synonym for “idiot” originated. Today, reader KH provided the answer. Here’s an excerpt from a New York Times article from March 21, 1897:
Many children are always mouth breathers, and cannot breathe through the nose on account of conditions of the throat requiring medical attention; in such children test the hearing, which is apt to become very dull if the case is neglected.
Apparently the original association, which was likely more true in 1897 than today, was “mouth breather” => deafness/difficulty hearing => mentally slow. And that’s your etymology lesson for the day.