If you clean your room of your own accord, your parents will be pleased—it means you did it without having to be asked. They might even accord you an extra privilege. Warring nations make peace accords.
A Honda Accord is a nice, agreeable car, and the word accord is all about agreement, or unity. If a whole class begs with one accord to postpone a quiz for a day to allow more review, the teacher is more likely to listen than if it was just one student asking.