A definition you probable unaware of.
An unused portion. A meal served for the first time.
1. A meal not yet touched by lips.
2. A freshly served meal.
3. Food before it has been eaten from by you.
Use example. Thank you for cooking. I am coming rightover for dinner.
Remaining as a used portion or amount of a meal.
1. A remnant of a meal.
2. Leftover food remaining from a previous meal
Use example. Oh crap. It is leftover dinner night.