Ukraine means «Fortified area» in Ukrainian or Polish. It's «укріплення» (fortifications) + «край»(area)/«країна»(country) = «україна». A modern Ukrainian word with the same meaning is «укріпрайон» (fortified area). It's started by Poland as a set of fortifications to protect eastern Poland against nomads from the East. Multiple ukrains were built. Ukrainian Cossacks were used for defense. When lines of defense covered large territory, the whole protected area received the name «fortified area» (Ukraine).

See https://en.wikipedia.org/wiki/Guillaume_Le_Vasseur_de_Beaupl... for details.

Russians are trying to downplay this and replace Oo at the beginning with Oh, to create Russian word Outskirt instead.