Proper nouns denoting nationalities (hence nationality nouns) in English have the morphological variation between singular and plural forms. Also, articles can appear in front of them. However, such variations are not consistently observed by all nationality nouns. In the paper, nationality nouns are classified into two categories according to the syntactic and morphological variations of the nouns. The paper finds that the final sound of a nationality noun being sibilant or not determines the classification of the noun. The nationality noun without the sibilant ending has the morphological variation of the singular vs. plural form. Such nationality nouns can also be preceded by the article the or a. With the predicate denoting general or particular situations, the various forms of these nationality nouns vary their meanings. Nationality nouns with the sibilant ending cannot be followed by a plural form which is also a sibilant. Such nationality nouns are plural in use, however. This affects the syntactic agreement between the nationality noun and other syntactic components as well as the composed meaning of the sentence.
