also: しゅうい · すうい
noun
abomasum
The fourth stomach compartment of ruminants; a technical term used in veterinary medicine and animal science.
牛の皺胃は第四胃とも呼ばれる。
The cow's abomasum is also called the fourth stomach.
From 皺 (wrinkle) + 胃 (stomach), referring to the folded lining of the abomasum.