I wrote "The thunder is still far away." It was marked incorrect, because it should be "thunderstorm" according to the given translation. But it says "onweer" in the Dutch sentence, which means thunder. Thunderstorm = onweersbui.
But thunder = "donder".
I would say that "onweer" describes weather conditions with thunder and lightning. There's not really a perfect word for that in English. Perhaps it would be good to accept thunder here, we'll discuss it.
"Thunderstorm" is a meteorological term. According to wikepedia, the Dutch equivalent is "onweer". https://en.wikipedia.org/wiki/Thunderstorm https://nl.wikipedia.org/wiki/Onweer Wiki says that "Een onweersbui is een regenbui waarbij ook onweer optreedt." https://nl.wikipedia.org/wiki/Onweersbui