عنوان مقاله [English]
Some of the nouns are called genus nouns. A Genus Noun refers to a category of nouns, each of which having a separate name. One of the means of indicating a genus noun in English is to use the -S suffix. In Persian Genus noun is used without any formal sign. Thus it is best to write Persian keywords in singular form wuthout a plural sign. There are instances whereby singular form keyword cannot be used. One such instance is when the term is popular among the experts, difference in definition of singular and plural noun, and obsolenscnce of the singular form. On occasions, the presumed term includes a class of exemplifications in which case the use of plural form is permissible. The type of plural suffix used exerts influence in popularization of the term.