hollow; cavity; dent; depression
hollow; low ground; basin; pit; dip; depression
hollow at nape of the neck; (arch.) toddler's shaved hairstyle leaving a small portion at the nape (esp. Edo period)
Ochikubo Monogatari; The Tale of Ochikubo (Heian period Cinderella story)
to cave in; to become depressed; to sink