粪便，又称屎，网络语言称米田共，是动物经肛门或者泄殖腔从消化系统中排出的废弃物。

食物被生物吸收部分养份后，剩余未被利用的部分，是属于排泄物的一种。

粪便的颜色是由胆色素引起的，粪便的气味是由粪臭素（3-甲基吲哚）引起的。一般为咖啡色。

Feces (US) or faeces (UK), also known by many other names, is a solid waste product from an animal digestive tract, discharged through the anus or cloaca during a process called defecation. Urine and feces together are called excreta.

Collected feces has various uses, namely as fertilizer or soil conditioner in agriculture, as a fuel source, or for medicinal purposes (fecal transplants or fecal bacteriotherapy, in the case of human feces).