invagination
/ɪnˌvædʒɪˈneɪʃən/noun
mass noun
1- chiefly Anatomy & Biology the action or process of being turned inside out or folded back on itself to form a cavity or pouch【主剖, 生】内陷。
1.1
- count noun a cavity or pouch so formed（内陷形成的）囊腔。
词源
mid 17th cent.: from modern Latin invaginatio（n-）， based on IN-2 'into' + Latin vagina 'sheath'.