Wiktionary
n. 1 (context graphical user interface English) An initial screen displayed by interactive software, usually containing a logo, version information, and a copyright notice. 2 (context Internet English) A splash page.
Wikipedia
A splash screen is a graphical control element consisting of window containing an image, a logo and the current version of the software. A splash screen usually appears while a game or program is launching. A splash page is an introduction page on a website. Splash screens cover the entire screen or web page, or simply a rectangle near the center of the screen or page. The splash screens of operating systems and some applications that expect to be run full-screen usually cover the entire screen.