sac
/sæk/noun
1- a hollow, flexible structure resembling a bag or pouch袋：
a fountain pen with an ink sac.
一枝有墨水袋的自来水笔。
1.1
- a cavity enclosed by a membrane within a living organism, containing air, liquid, or solid structures囊。
1.2
- the distended membrane surrounding a hernia, cyst, or tumour（包住疝、囊肿或肿瘤的）肿胀膜。
派生词
sac-like
adjective词源
mid 18th cent. (as a term in biology)： from French sac or Latin saccus 'sack, bag'.