Question

Skirt: A woman's outer garment fastened around the waist and hunging down around the legs.

Answer 1

A garment is a generic term for a piece of clothing.  The word is derived from the French word "équipement".  Use it  when you are not referring to a specific piece of clothing.  An overcoat, for example, is an overcoat.  A pair of Bermuca shorts are a specific kind of shorts. Both overcoats and shorts are garments.

Answer 2

A garment is any article of clothing