Proprietary means owned and controlled by a particular person or company. When something is proprietary, only the owner has the right to make it, sell it, or decide how it's used.

A proprietary recipe is one that a restaurant keeps secret because it gives them a special advantage. The formula for Coca-Cola is proprietary: the company owns it and guards it carefully so competitors can't copy it. Video game companies use proprietary technology that only they can use in their games.

The word often appears in business and technology. Software can be proprietary, meaning you have to buy it from one company and can't freely copy or modify it. Microsoft Windows is proprietary software. By contrast, open-source software is the opposite: anyone can use, study, and change it freely.

When you buy something proprietary, you're usually agreeing to follow the owner's rules about how to use it. A proprietary phone charger only works with one brand of phone because that company designed it specifically for its products. Sometimes this protects the company's innovations and investments. Other times it frustrates customers who wish they had more choices and flexibility.