Variable noun (vn):可算にも不可算にもなる名詞
Variable nouns are nouns which combine the behaviour of count and uncount nouns. They are like count nouns when they refer to an instance or more than one instance of something.
Otherwise they behave like uncount nouns, referring to a substance or thing in more general terms.
https://grammar.collinsdictionary.com/grammar-pattern/variable-nouns
・vn: cargo 貨物