Urban Dictionary OOTNnighttime outfit heart meaning is a phrase used to describe an attire that is put on during the night or for special occasions. symbolizes love, passion, and affection. Therefore, an ootn showcases an stylish and captivating attire that mirrors one's love for fashion and enjoys the evening vibe. Wearing an ootn can boost your confidence, make an impression, and display elegance and charm. No matter it's an glamorous dress or a chic suit, the ootn guarantees that you catch everyone's attention and leave a lasting impression at any evening event.