Abstract
This article discusses the history of the study of the law of singarmonism (harmony) in Turkic languages and its place in the modern language system. Singarmonism is based on the combination of vowels with each other as one of the phonetic patterns characteristic of Turkic languages. According to this law, the vowels in a word are either thick or thin, obeying lip harmony and maintaining a single phonetic shade as a whole. The article analyzes in detail the phonetic, morphological and historical aspects of this phenomenon. In the course of the study, the manifestations of singarmonism from ancient Turkic written monuments to modern Turkic languages are considered on the basis of a comparative-historical method. In addition, on the basis of the works of Turkologists of different periods – V.V. Radlov, A.N. Samoilovich, E.D. Polivanov, N.K. Dmitriev, S. Amanzholov and others, the evolution of the theoretical study of singarmonism is shown. The article compares the features of the laws of harmony in the languages belonging to the Altai language group, identifies their common and singular characteristics. Also, the influence of the modern process of globalization and linguistic changes on the law of singarmonism, the causes of its violation and the disappearing or preserved forms of the law are analyzed on the basis of language materials. The results of the study show that singarmonism is not just a historical and theoretical phenomenon, but an active linguistic factor that plays an important role in the development of modern Turkic languages.