If you spoil yourself or spoil another person, you give yourself or them something nice as a treat or do something special for them. Spoil yourself with a new perfume this summer Perhaps I could employ someone to iron his shirts, but I wanted to spoil him. He was my man. = pamper
hinder or prevent (the efforts, plans, or desires) of; "What ultimately frustrated every challenger was Ruth's amazing September surge"; "foil your opponent"
If someone spoils their vote, they write something illegal on their voting paper, usually as a protest about the election, and their vote is not accepted. They had broadcast calls for voters to spoil their ballot papers = deface
the act of stripping and taking by force the act of spoiling something by causing damage to it; "her spoiling my dress was deliberate"