The article deals with variant words in the Turkic languages. From the historical point of view the significance of synharmonic variants and parallels is in the following: the phenomenon plays a special role in a methodological aspect in order to restore ancient roots and phonemes in their previous forms. We vividly observe the fact when we compare words pronounced via forelingual vowels with words pronounced via backlingual vowels. Comparing words pronounced through forelingual vowels with words pronounced through backlingual vowels we have made the following conclusions. In the result of language development during a long period of time backlingual and midlingual vowels and consonants moved to the front part of a tongue. Indisputably this is the influence of natural conditions, the change of physical qualities of a man (height fall, constitution decrease, etc.)

We have analysed hard variants of words having become softened in the Kazakh literary language or its dialects may present much more materials in this respect. Historical written memorials that reached our time prove the absence of soft pronounced sounds and the usage of their hard variants. Having researched and analysed carefully the words pronounced with soft vowels in Turkic (including Kazakh) languages we can restore almost all of them in their hard forms as in ancient Turkic because hard variants pronounced softly at present can be observed in one or other Turkic languages, their dialects, set expressions, onomastics, toponimics, historical writings, etc. This article analyzes controversial issues in the study of variant words in the Turkic languages