Cross-platform refers to the ability of a program or application to run on multiple platforms, such as different operating systems, hardware architectures, and mobile devices. This means that developers can write code once and deploy it across various platforms without having to rewrite or modify the code for each platform. JavaScript is well suited for cross-platform development due to its ability to run in any web browser or native application. Cross-platform development allows developers to create applications that can be used on any device or system, making them more accessible and easier to maintain.