/si:l ||; sil/noun[C] 1 a grey animal with short fur that lives in and near the sea and that eats fish. Seals have no legs and swim with the help of short flat arms(flippers). 海豹
2 an official design or mark that is put on a document, an envelope, etc to show that it is genuine or that it has not been opened 封蜡；火漆
3 a small piece of paper, metal, plastic, etc on a packet, bottle, etc that you must break before you can open it 封口；封条
4 something that stops air or liquid from getting in or out of something 封塞；封口: The seal has worn and oil is escaping. 封口破损了，油正往外渗漏。