Narrow.
'D' and/or 'M' is the shoe size width measurement, and indicates a medium or standard width. Sometimes the shoe width size will be indicated with only a 'D' or 'M.' Furthermore, a 'C' width would be narrow width, an 'E' width indicates a wide width, and an 'EE' width would be extra-wide. If you're seeking detailed information on the exact width measurements, measured in inches, there should be some U.S. shoe size width charts available on the internet, found using the keywords, "US shoe size width chart."
YAY! (=
When you go to shoe store, they have this feet measurement. It measures both your shoe length and width.
It indicates width of the shoe. B is standard width in ladies' shoes, D is wide.
It can vary from 3-8 mm in width, on average.
A 13C shoe size indicates a shoe that is a child's size 13 in width C. The letter C stands for a medium width, which is common in most shoe sizes. This size is typically suitable for young children who have average width feet.
a double size
wide width
EEE
a double size
M means medium, and is a reference to the width of the shoe, not the actual size.