The word emergency used to mean anything that emerged. The first use was in the 17thcentury when someone described corpses emerging from a lake. People used to say there was an emergency of flowers in the springtime. It wasn’t until the late 19th century that it meant what it means to day.
If anyone is actually interested in the history of word origins and definitions, go to the library and check out the Oxford English dictionary. It sounds geeky, but it’s really interesting to look up random words and see where they came from and how they changed.
If you’ve got more money than you know what to do with, you could get a subscription online to OED. It’s 300 bucks a year. I’d check and see if your local library or university grants access first.