Definition from Wiktionary, the free dictionary
Alternative forms 
leftover (not comparable)
- Remaining; left behind; extra; in reserve.
- Do you want some of the leftover supplies from the event?
- (chiefly plural, usually of food) Remaining after a meal is complete or eaten for a later meal or snack.
- I have some leftover spaghetti in the fridge, so I don't plan to cook tonight.
- Not leftovers again.
Usage notes 
- When used after a verb (as part of a predicate phrase), use two separate words:
- I can walk for miles and still have energy left over.
remaining, left behind
remaining as meal is complete
leftover (plural leftovers)
- Something left behind; an excess or remainder.
- It's a leftover from yesterday, but it's still perfectly good.
- The entire wheel of cheese is a leftover from the party.