The present study deals with ambiguity at word level focusing on homographs. In different languages, homographs may cause ambiguity in text processing. In Persian, the number of homographs is high due to its orthographic structure as well as its complex derivational and inflectional morphology. In this study, a broad list of homographs was extracted from some Persian corpora first. The list indicates that the number of homographs in Persian corpora is high and homographs with high frequency are those that occur as a result of the identical orthographic representation of some inflectional and derivational morphemes. Based on the list, the most frequent homographs are nouns and adjectives ending in <ی> /i/. POS tag disambiguation of such homographs would make word sense disambiguation easier and lead to better text processing. In this study, a list of noun and adjective homographs ending in <ی> is extracted in order to decide their correct POS tag. The result was studied to extract context-sensitive rules for allocating the right POS tag to the homograph in syntactic structures. The accuracy of rules was checked, and the result showed that the accuracy of most rules is high which proves most rules are true.