The float words or Mofradā t is a class of words that they haven’ t fix morphological labels. In other words, these words are placed between morphology and syntax. On the other hand, they are words and on the other hand, the determination of their exact meanings is depended on consideration syntactic relations and their places. So, they are morphological-syntactic categories. Therefore, they must be measured in terms of other words of the sentence to attribute to one of the syntactic categories in Persian grammar. This article – by descriptive-analytical method-tries to explore these words in Kamal al-Din Hossein Khwarizmi’ s Irš ā d al-Morī dī n. The results of this research show that the float words of this text are: “ bas / basi” , tā , č and/ č andī n, č onī n/ č onā n, č o/hamç o, č oon/hamč oon, č e, degar/digar, ke, magar, ham, hame, and hī č . Many of these words have grammatical functions such as adverb (interrogative, cause, conditional, exceptional, uncertainty, increasing, negative and arrangement), adjective (quantity, interrogative, indefinite and exclamatory), preposition, subject, conjunction, pronoun (indefinite, interrogative, non-interrogative and numeration). Meanwhile, “ ke” is the most usable float words in this text. The next clauses of it have the functions of non-interrogative pronoun, conjunction, subject, adjective, object, time and condition adverb.