"PJ" is a well-known abbreviation for pajamas, but there are plenty of other words and phrases that can be used to describe these comfortable garments. Synonyms for "PJ" include nightwear, sleepwear, lounge clothes, jammies, nightclothes, nightgown, nightdress, nightie, sleep dress and more. PJ's or pajamas are designed to be worn while sleeping to keep the body comfortable and relaxed. These synonyms for the word "PJ" describe a variety of garments that can range from stylish silk or satin nighties to cozy flannel pajama pants. Whatever your personal preference, there are various synonyms that can be used to describe these nighttime clothing items.