Wiggle Dress is a dress where the width of the hem of the dress is narrower than the width of the hips.
Because of that your legs are close together at the knees, and that causes the 'Wiggle' when you walk.

50s Black Lace Cocktail Party Wiggle Dress.
* Black floral lace * Satin waist * Acetate lining * Sweet cap sleeves * Metal back zipper * Black lace has a slight red cast * "Hayes" * Metal side zipper

50s Brown Tweed Cocktail Wiggle Dress Jacket Set.
* Brown tweed * Wiggle dress * Metal side zipper * Original matching belt * Matching jacket * Acetate lining * Button front * Velvet trim * Lipman Original