The practical research and studies on the lexis of one, two and/or several languages and the confrontation of the same or quasi-similar words have always been among the most interesting topics in linguistics and other relevant humanities, i.a. Translation Studies and Foreign Language Teaching. From the point of view of Comparative Linguistics, the mentioned words can be classified into three general groups, namely related, borrowed and accidental groups. The latter, which until recently did not exist as an independent group and under this name, and had not been precisely researched, consisted of the false friends in the studies of the disciplines mentioned. The obvious aims of the present research include primarily the mainly theoretical and qualitative (descriptive-analytical) investigation and re-categorization of common (accidental) words of any non-/related language pair in general and then determining the position of unconscious friends as a new, unfamiliar, and low-frequency subcategory of accidental word pairs among the triple categories of common words of the language pairs. In this regard, the author has used some corpus examples from her research on Persian-German word pairs, i.a. the previously mentioned subgroup, which is here debated for the first time in Persian and analyzed beyond the above languages. Rather, further examples relate to the broad spectrum of so-called Indo-European and Semitic languages. The results of this lexeme-based research indicate that not only are the unconscious friends unknown in the linguistic field, but also other, well-known word pairs in this and other subjects have not been precisely examined and classified.