Abstract: The object of this research is the problems of functionality of Iranian and Semitic loanwords in the Ancient Greek language, while the subject is the lexemes παράδεισος, γάνος, γανναθ, (αλ)γοναιναθ. The authors meticulously examine such aspects of the topic as the morphological and phonetic assimilation of foreign language lexicon, nonobservance of phonotactics of the Greek language, impact of folk etymology upon the word form , absence of diacritics in conveying Semitic borrowings in the Greek language. Special attention is given  to the problems of etymologization, nuances of dictionary definitions throughout different periods: classical, Hellenistic, Hellenistic-Roman, Late Antique, and Byzantine. It is noted that over time, close ties with barbarian peoples affected the Greek language itself. The main conclusion consists in determination of the gradation of lexemes under review in accordance with the degree of their adaptation to the Greek phonetics and phonotactics, as well as morphology. The author's special contribution to this research consists in proving the results and conclusions of a range of previous studies, as well as in critical coverage of the controversial concepts. The novelty lies in the proposed etymology of the lexeme παράδεισος, and the new interpretation of its vocalism. The relevance of this work lies in involving rare lexicon, which previously has not received due attention within the existing scientific tradition.