"Naughty" is a good dictionary definition and is appropriate when talking about children, perhaps. But not when talking about a camel. We learn as we go that there is more to the language than inserting a certain word every time. Context greatly influences our choice.
In English, we also talk of pets being naughty. Dogs, cats, ponies, and horses can be called naughty. Camels are mean but I suppose a mischievous one could be described as naughty by a zookeeper or a camel jockey.
Please - we are not all from the US. 'Mean does not mean the same thing in other places
What would you say in your neck of the woods? Do you think your word is widespread enough to be included in the answer bank? Have you reported it?
This camel is nasty - rejected. Méchant means nasty. If you want to say "That camel is mean", it would be "Ce chameau (la) est pingre." In English, "mean" means stingy, miserly or mingy. I think in US English, "mean" means "really cool" as in "mean machine". So maybe you should change to a less ambiguous term. Is the camel supposed to be a "mean machine" or is it just careful with its money?
In US English the most common meaning for "mean" is not "really cool". It's almost the opposite.
If you're being mean to someone then you're intentionally being cruel to them for no goid reason.
How about vicious? It was accepted back when we were doing 100 sentences about un chien méchant. And "vicious" is a word used all over the Anglo world, unlike the regional variants being used now.
ETA: I just used vicious and duo let it slide.
Méchant means naughty. Not mean. That's how I learned it over 30 years ago and just checked it out with my daughter who recently got an A in her French A level
My personal experience with well cared for camels is that they do not deserve their "mechant" reputation. They can be rather charming!!
I originally thought that 'méchant' was 'naughty' and could be applied to children. However I get the impression from its use in Duo Lingo that there is a rather more unpleasant side to the meaning of it. Is that correct? However I have found so many other English translations of it, eg mean, bad, vicious , spiteful, wicked, mischievous, that I think they should all be accepted (unless obviously it doesn't fit the context) and different ones should not be a reason for marking the translation wrong since the rest of the sentence is more important in learning the language.