submucosa
noun [ C ] anatomy specialized uk/ˌsʌb.mjuːˈkəʊ.sə/ us/ˌsʌb.mjuːˈkoʊ.sə/ submucosae
粘膜下层
the layer beneath the mucus membrane (= the thin skin that covers the inside surface of the nose, mouth etc. and produces mucus to protect them)