What is "advents"

Usage examples of "advents".

He knows we live in a world that loves to think SF, and has thought SF ever since Hiroshima , which was the ne plus ultra of Millennial Technological Advents, which really and truly did change the world forever.

The Thombo tablets are straightforward historical accounts of two separate advents of the Stars thousands of years ago, and of the attempts made by the priesthoods of the time to warn the populace of what was about to happen.