Uneven numbers in the sizes are for body shapes that are shorter in the shoulder-to-waist or waist-to-crotch than the even numbered size. Sometimes and odd-number sized person can wear an even-number size, depending on style or manufacturer (and vise versa).

Of course, no two manufacturers use the same size chart!

I can wear a size 8 in pants if the manufacturer is a high class one and a 12 if I go to K-Mart. Same butt.