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Wiktionary
bootsplash

n. (context computing English) A splash screen displayed at bootup.

Wikipedia
Bootsplash

A bootsplash can be a simple visualisation of the scrolling boot messages in the console, but it can also present graphics or some combinations of both.

Unlike splash screens, bootsplash is not necessarily designed for marketing purposes, but can be to enhance the experience of the user as eye candy, or provide the user with messages (with an added advantage of color-coding facility) to diagnose the state of the system.