Under-garment n. : A garment worn below another.

Example:
What is the purpose of the Mormon under garment and do you wear it all times?

Taxonomy
underwear, undergarments, briefs, garment, corset, waist, boxer shorts, clothing, Women's undergarments, fashion, legs, pouch, company, brassiere, body, waistband, men and women, decade.

Defination from the web:
garment to alter a woman's body shape. ... wear camisoles and slips (petticoats) under clothes that are sheer. ...