Synallagmatic

Synallagmatic is an adjective that means imposing reciprocal obligations.

Coming from the Greek word for contract, our word of the day is often used in legal situations, refers to the need for both sides to offer the same. Here’s an example:

I refused to accept any terms that were not synallagmatic. If I was going to wash her car for a week, she had to wash my skateboard for a week.