Spoiled means given so much that behaviour has suffered. A spoiled child, spoiled rotten, thoroughly spoiled.
Spoilt is the commoner British form and spoiled the American, and both are correct. Spoiled rotten is the fixed phrase. Of food it means gone bad, and of an event it means ruined: the whole day was spoiled. A spoiled ballot is one marked so that it cannot be counted, sometimes deliberately. Note spoil, spoiler; and that spoiling somebody is also affectionate — being spoiled for a birthday is entirely good.
1adjectivespoiledGiven so much that behaviour has suffered.
“The spoiled child screamed when he didn't get another toy.”
2adjectiveruinedRuined or gone bad.
“The milk was spoiled, so I had to pour it away.”
Too few real examples of this word to estimate which sense is commonest.
spoiled is a state of being over-indulged or ruined.