The vocabulary, which is formed with the words in a language in the historical process and can be defined as a corpus, can change according to the needs arising, separately for each word. Some words in the vocabulary, which is one of the indicators of the richness of the language, undergo changes in meaning in the historical process in line with the needs of the language. These changes in meaning can occur in the forms of meaning contraction, meaning expansion, meaning improvement, meaning deterioration, etc. The process a word goes through to undergo a change in meaning is long-lasting. In this respect, the relevant word must exist in the language for a long time. The meaning of a word is determined at the syntactic and syntactic levels. However, semantic relations are also important. This study discusses how vocabulary in a language can change over time, specifically focusing on the words oğul and its plural oğlan which means son and sons in Turkish. The study examines the etymology of these words and explores the changes in meaning they have undergone throughout history. The meanings of oğul and oğlan are analyzed in relation to semantic relations, both diachronically and synchronically. Historical texts serve as evidence for these analyses. Additionally, other words derived from oğul and oğlan are also studied, as they are used with similar meanings. Overall, the text emphasizes that the process of meaning change in a word is lengthy, and highlights the importance of syntactic and semantic levels in determining a word's meaning. The Arabic words "tıfıl, iyal, velet, evlat", which have the same meaning as the words oğul and oğlan, which are the subject of our study, are frequently encountered in our historical texts. Altought Our study is limited to Turkish words.

Oğul, oğlan, diachronicity, synchronicity.