The article examines the phonetic and etymological aspects of the Old Turkic verbs qod- and qudto
determine whether they represent two distinct lexical items or phonetic variations of a single verb
root. By analysing Old Turkic inscriptions in different writing systems, including Turkic Runic, Brāhmī,
Manichaean and Uighur scripts, the research explores how the vowel change o ~ u is recorded in
historical sources. It takes a comparative approach, examining how these forms appear in different
Turkic languages and loanwords in neighbouring languages such as Yeniseian and Slavic. The study also
assesses the impact of phonological constraints and orthographic conventions on the transcription of
these words. The results suggest that qod- and qud- were historically intertwined, and probably derived
from a single root meaning ‘to lower something’ or ‘to move something downward’. Over time, phonetic
shifts and dialectal differentiation led to distinct forms that influenced later developments in Turkic
languages. The article contributes to the broader discussion of vowel shifts and phonological variation
in historical Turkic linguistics
