A more thorough explanation:

defeat, verb

1. To take away something expected from someone, usually by acting against them. Example: "The candidate defeated his opponent in the election."
2. To cancel or make something invalid. Example: "The court defeated the title to the property."
3. To conquer or overcome someone or something. Example: "The army defeated the enemy."
4. To prevent something from happening or working. Example: "The expenses defeated the purpose of the bill."

These examples illustrate how defeat can mean taking away something expected, canceling or making something invalid, conquering or overcoming someone or something, or preventing something from happening or working.