Ferit Devellioğlu (1906–1985) is a researcher and author known for his contributions to Turkish lexicography linguistics and translation. His most renowned work is the Ottoman Turkish–Turkish Encyclopedic Dictionary.^【1】

Ferit Devellioğlu was born in Istanbul in 1906. He began his education at Beyazıt Rüştiyesi and continued his studies at the Kumkapı French School after graduating. It is widely accepted that the foundations of his linguistic and grammatical knowledge were laid at Kumkapı St. Jeanne d’Arc French School and Kumkapı Assomption French College, institutions run by nuns and priests and offering instruction in more than two foreign languages. He completed his secondary education and graduated from Galatasaray High School (Mekteb-i Sultânî). Growing up and spending his youth in Kumkapı, a multicultural neighborhood where Muslim and non-Muslim communities lived together, provided him with a broad cultural foundation.^【2】

^{Ferit Devellioğlu Infographic (Generated by Artificial Intelligence)}

After graduating from Galatasaray High School, he worked for six years as a translator at Banque Générale pour le Commerce Étranger, a French bank. In 1933, following the decisions of the First Turkish Language Congress held by the Society for the Investigation of the Turkish Language—established in 1932 under the directives of Mustafa Kemal Atatürk—he began working as an expert in the “lexicography and terminology” section. During his 43-year service at the Turkish Language Association, he held positions not only as a lexicography expert but also as secretary general and head of the publications department. He retired from his position in 1974 and officially retired in 1976. He also contributed to the 1955 edition of the Turkish Dictionary prepared by Mehmet Ali Ağakay and participated in the committee that prepared its fifth and sixth editions in 1969 and 1974.^【3】

Devellioğlu’s most significant and renowned contribution to scholarship is the Ottoman Turkish–Turkish Encyclopedic Dictionary, first published in 1962. This comprehensive work, containing over 60,000 entries, was compiled with reference to personal notes by Kemal Edip Kürkçüoğlu and Osman Nedim Tuna. After the author’s death, the dictionary was revised and expanded in 1993 by Aydın Sami Güneyçal with significant additions. The 2010 edition, again under Güneyçal’s supervision and with contributions from academics, was further enlarged with the inclusion of an alphabetical index, compound words, and idioms, bringing its total page count to 1,712.^【4】

Another major contribution to lexicography is his study and dictionary Turkish Slang, published in six editions between 1941 and 1980. This work is the third slang dictionary published in the history of Turkish Turkish, following the studies of A. Fikri and O. Cemal Kaygılı. The book examines the definition, origin, etymology, place in Turkish literature, and characteristics of Istanbul slang using a scientific approach. Notable figures of the era, Nahit Sırrı Örik and Hikmet Dizdaroğlu, wrote introductory and evaluative essays on this work.^【5】

Devellioğlu translated the work Turkish Ethnic Elements in Dobruja (1942) by the French-born Turkologist Tadeusz Kowalsky into Turkish, enriching the fields of Turkish dialectology and folklore. In addition to his lexicographical works, he published numerous articles in academic journals. Notable among these are “Babel Towers in Our Turkish” (1959), “Advice to the Language Judge” (1960), “Music in Turkish Slang” (1967), and “On a New Dictionary” (1970).^【6】

^{Ferit Devellioğlu / Ottoman Turkish–Turkish Encyclopedic Dictionary} (İş Bankası Kültür Yayınları)

In addition to his linguistic expertise, Devellioğlu possessed profound knowledge of Turkish music. In his dictionaries, he did not merely note musical terms such as hicaz, nihâvend, and rast as “musical modes”; he provided scholarly explanations for these terms, as he did for medical, legal, and literary terminology, and included relevant examples. This academic contribution also facilitated the development of other researchers such as Cem Dilçin.^【7】

• French–Turkish Dictionary of Colloquial Expressions (1937)
• Turkish Slang / Turkish Slang Dictionary (1941, 1970)
• Turkish Ethnic Elements in Dobruja (1942, translation)
• Ottoman Turkish–Turkish Small Dictionary (1949)
• Ottoman Turkish–Turkish Encyclopedic Dictionary (1962)
• Ottoman Turkish–Turkish School Correspondence Dictionary (1964)
• The Newest School Dictionary (1972)
• Twelve-Thousand-Word Turkish Dictionary (1972)
• French–Turkish Idioms Dictionary (1973)
• Ottoman Turkish–Turkish School Dictionary (1975)
• The Newest Large Turkish Dictionary (1975)^【8】