Through the passage of time, the forms and meanings of words in languages often change due to linguistic and non-linguistic factors. In this process, the same word may change to different forms in cognate languages ; it means, for example, its usage may decrease in one language and, conversely, increase in another. The historical background of the old Iranian word “*daiman-: eye” proves this statement. The oldest Iranian text in which this word is found is the young Avestan. This word is not used in modern standard Persian. On the contrary, it is common in modern Balochi language, one of the known Iranian languages, with relatively numerous derivatives and compounds. This article, with a semantic approach, seeks to answer in a descriptive manner the question as to what data is used with the aforementioned word in modern Balochi and, to some extent, what differences it shows in terms of comparison with Persian. The results based on two reliable sources in these two languages, the Sokhan Comprehensive Dictionary, by Hassan Anvari, published in 2002, and the Balochi-Persian Dictionary, by Abdul-Ghafoor Jahandideh, published in 2017, show that this word is described in the Sokhan Comprehensive Dictionary with only one entry as an "archaic" word, while in Balochi it is given with 172 entries and sub-entries with different derivatives and combinations. The results of this research indicate that to achieve the historical background of Iranian words, studying them only in a language like Persian, which is currently the most prestigious Iranian language, is not sufficient, and in this context, the role of other Iranian languages such as Balochi, Kurdish, Pashto, Gilaki, and Ossetic should not be neglected.