Anyway, on to lower-case eve. This venerable little word harks back to about 1200, when it meant the time between sunset and darkness, as it more or less does today. It comes from the Old English word æfn, but at some point the final "n" was dropped, which is retained in today's more common "evening."
I hardly need mention – though of course I will – the several other uses of eve's forbear, even: The ground is even. Both sides are even now. Even me!? Two, four and six are even numbers.
And then we have the inevitable colloquialisms that arise in all human speech. They provide some of the spice in languages, even for common little even. People became even-tempered in 1712 and didn't start getting even until 1833. Shortly thereafter, they began to sort things out when in 1866 they learned how to make things even-steven. It took until 1907 for anybody to get an even break.
Then there was Eve in the garden with Adam. Her name comes from the Hebrew word Hawwah and means "a living being." So every living thing could be called Eve. I like that. Derivatives of her name are Ava and Eva, and perhaps it also got extended to Evelyn.
And there you have it – more than you ever thought there was to learn about one tiny little gift to the English language.