I wrote "huge" as a translation of "gross", and was marked wrong. My dictionary says otherwise.
I'm not an expert in German (yet?) but my impression is that "huge" is quite a bit larger than "gross". "Riesengroß" would be more like "huge".
Good point, but my complaint was that "huge" is not actually a wrong translation of "gross". It may not be the best, but it is not wrong. These are the two words given for "huge" in my dictionary:- gross; riesig. If I look up "enormous", I get ungeheuer. If I look up "gigantic", I get riesenhaft. I suppose, as Heike333145 suggests (among other things) the best translation of English "huge", is probably "sehr gross" in German.
As I said, it depends on the context. "Huge" may be wrong in the given sentence.
Dictionaries give all the possible translations of a word. But from these dictionary translations, you have to select those that fit in your particular context, for example: Does the sentence refer to a person or an object? Some words are allowed for objects, but sound weird and wrong when used for persons.
So the correctness and appropriateness of a translation can only be determined in the given context.
And that's why you should report your sentence: The team will then assess whether your translation is OK within that particular sentence.
When you do the exercises, there is a button "My answer should be correct" (or similar). You can use that button to suggest to the Duolingo team to add your response to the possible solutions.
I think it depends on the sentence whether "huge" really fits. The German adjective "groß" tends to be used in a much broader sense than "huge". "Huge" is rather "enorm", or "sehr groß" or "gewaltig".
I think the button is "Report problem". Then "My answer should be correct" is one of the possible selections after pressing that button.
Duolingo and hanspersson are correct here: "huge" is rather bigger than "groß", and you'd rather go for something like "riesig" or "enorm" for "huge".
May I ask what dictionary you're using? Your translation isn't given in Pons, Langenscheidt, Collins, Cambridge, Wiktionary, or even in dict.cc (which tends to follow a "quantity over quality" policy in its translations). I'd suggest looking at other dictionaries -- http://pons.eu/ is my favourite for everyday use.
Collins dictionary. As I said elsewhere, it may not be the best translation, but my point is that it is not actually wrong. As Heike says, it depends on context, but we don't have any context in these lessons. I accept unreservedly that "big" would have been a "better" translation without knowing any more about the context.
Strange, I don't see it at https://www.collinsdictionary.com/dictionary/german-english/gro%C3%9F . But there's doubtless more than one Collins German-English dictionary.
As regards "not actually wrong", I think it's useful to remember that the goal here is teaching. If rare, heavily context-dependent translations like "huge" are accepted, students will get the impression that these are generally acceptable translations. From the Collins page, you can see that -- in the right context -- "groß" can also be translated as "terrible", "summer", or "lunch". I wouldn't want these accepted either. I think that, where context is absent, it's better to restrict the accepted translations to those that work in general, rather than in only a few specific situations.