愉 means 'pleasure'

These four essays provide the key to happiness. With 暇 one has free time, whether a vacation, a leave of absence, or simply time to kill. Then 娯 provides destinations for having structured fun, including amusement parks, theaters, or venues for karaoke, pachinko, or horse races. With 愉 people relax into a carefree sense of fun and pleasure. And with 悦 one can experience joy and delight in a variety of things, including hospitality, a sense of progress, food, artistic masterpieces, a college acceptance, religious rapture, and sexual ecstasy.