In grammar, a lexical category (also word class, lexical class, or in traditional grammar part of speech) is a linguistic category of words (or more precisely lexical items) that are usually defined by their particular syntactic or morphological behaviors. Common linguistic categories include noun and verb, among others. There are open word classes, which constantly acquire new members, and closed word classes, which acquire new members infrequently if at all. Different languages may have different lexical categories, or they might associate different properties to the same one. For example, Spanish uses adjectives almost interchangeably as nouns while English cannot. Japanese has two classes of adjectives where English has one; Chinese and Japanese have measure words while European languages have nothing resembling them; many languages don't have a distinction between adjectives and adverbs, or adjectives and nouns, etc. Many linguists argue that the formal distinctions between parts of speech must be made within the framework of a specific language or language family, and should not be carried over to other languages or language families.