See-through clothing is clothing made of non-opaque material, often similar to (though usually thicker than) what is used for tights. Obviously, this allows people to see the wearer's skin almost as if he or she were naked or scantily clad. The wearer may have lingerie underneath to avoid being indecent, or on the contrary go commando to avoid lingerie being visible.
Ordinary clothing may allow some see-through; for example, some leggings do, especially if the wearer is bending over so that the material is stretched. Skin-tight clothing may become see-through if the material is stretched so that it becomes thinner; this may happen in particular with leggings. A white blouse may be sufficiently see-through to allow a black bra underneath to be detectable.
A hula skirt or grass skirt is a skirt consisting of a collection of strings hanging from a waist band. If there are enough strings, the skirt may be opaque if the wearer is standing still. However, inevitably there wil be see-through if the wearer moves around energetically. Often, one leg may protrude through the skirt as with a slit skirt.