Dangling parens are the loose closing parens on separate lines. I.e. this: (defun plus (x y) (+ x y) ) instead of this: (defun plus (x y) (+ x

Dangling parens are the loose closing parens on separate lines. I.e. this: (defun plus (x y) (+ x y) ) instead of this: (defun plus (x y) (+ x y)) It suggests the author tires to balance parens manually/visually rather than using a proper editor mode. An understandable and common mistake of a newbie, but looks bad when you are writing a tutorial.