In Old English, “ǣfentīd” was used for the end of the day, while “ǣfnung” referred specifically to the time of dusk falling. It’s from the latter that we get the modern English “evening” — while it was a more specific term in Old English, it evolved to refer to the general time frame from about 6 p.m. to 10 p.m. “Eventide” came from the former Old English root, and you can use it as a more poetic synonym for “evening.” Old English also gave us a few other alternative words for time descriptions; a moment is precisely 90 seconds, and a mileway is about 20 minutes, or how long it takes to walk a mile.