Spoil sb rotten informal verb phrase
To indulge someone too much, especially a child, making them demanding and think they will get everything they want.
It's understandable that grandparents indulge their grandchildren too much and somehow spoil them rotten.
Jack is a demanding person since his mother is always giving him what he wants. I guess she has spoiled him rotten.
To interfere somebosy's plan or bussiness
Spoil or undermine someone's plans or chances
To spoil something with something else
1. To contaminate something with toxic substances.
2. To spoil, damage, or degrade anything positive by the presence or introduction of something awful, sad, or terribly unpleasant.
To spoil or ruin something; to mess something up
The verb "spoil" should be conjugated according to its tense.
The phrase originated from the older sense of the word spoil in English, meaning to strip the armor and weapons from a slain enemy. From here, the word came to mean the items that were removed, booty or plunder, hence our word spoils, as in phrases such as “the spoils of war”. It then took on a literal meaning of depriving someone's quality or distinction, and later still to impair or damage something to the extent that it became useless. By the end of the 17th century, the word spoil meant to overindulge, hence we have the phrase as we know it nowadays.