There is a way to have Wikipedia loaded on your computer so that you can view it when you don't have access to the Internet. It's called XOWA, and it's compatible with Microsoft Windows, OSX, Linux and Android.

XOWA allows users to download and import their own copy of Wikipedia using official database dumps, or by special hosted database files specifically created for use within XOWA. The application is designed to accurately display Wikipedia content through its own built-in browser, or by an internal hosted web server which allows users to access content using a browser of their own choice.

XOWA can load and display multiple wikis. It is not limited to just Wikipedia.

For instructions on how to download and install it, see the official XOWA webpage.