The term SLUMBER PARTY WEAR refers to clothing typically worn to a slumber party. NIGHTIE, which is seven letters long, is a loose-fitting nightgown usually made of cotton or silk. PJS, which is three letters long, is an abbreviation for PAJAMAS, which are loose-fitting two-piece garments consisting of trousers and a shirt. PAJAMAS, which is seven letters long, is another word for pjs. All of these items of clothing are comfortable and suitable for sleeping in.