'Expressive' means that it's easy to write code that's easy to understand. JS doesn't even come close to the expressiveness that you get in C# due to the fact

'Expressive' means that it's easy to write code that's easy to understand. JS doesn't even come close to the expressiveness that you get in C# due to the fact that in JS, you don't even know the type of arguments being passed in any given function without looking elsewhere in the code - therefore, it's not easy to understand. If you're going to go with the definition that says expressiveness means "the variety and quantity of ideas that can be expressed", Javascript also loses there since there are whole classes of behavior that cannot be practically expressed in Javascript. For instance - try writing a function that only accepts a standard single precision floating-point number as it's argument and see how much work you have to do compared to other languages. Try expressing a Dictionary, Linked List, HashTable, SortedList, SortedDictionary, etc in JS - you'll be writing those structures yourself or cobbling together some random lib. Better languages let you actually express those things without having to write them yourself.