leftover
n. countablen. food that remains after a meal has finished. You usually save it to eat later.
n. an unused portion or remaining quantity of food from a previous meal. Frequently used in the plural form to refer to a complete meal made from remains.
I will eat the leftover pizza for lunch tomorrow.
She packed the leftover turkey into small containers to freeze for future soups and stews.
While some diners find the prospect of eating a leftover unappealing, many traditional recipes were specifically designed to transform yesterday's remains into a completely new culinary experience.
From left (“remaining, abandoned”) + over (“excess”).
Commonly used in the plural ('leftovers') when referring to the food itself; the singular form is more frequent as an adjective before a noun.