Pigswill is leftover food — often wet, mixed, and no longer for people — that is given to pigs to eat. Farms, and in older times households, would save scraps, peelings, and kitchen slops, and that mix was pigswill. It is a blunt, slightly old-fashioned British-leaning word, and it sounds messy on purpose. People also throw it as an insult at very bad food (“this is pigswill”), though that is rough talk. Though actually, you will not hear it much in careful writing now; leftovers or slops is what many speakers would say. It is farm language first, a rude food-word second.

餿水、豬食（廚餘拿去餵豬的那種）。不是「豬的飲料」。