Prof. Yordan Zaimov was born on April 23, 1921 in the city of Sofia. Graduated in Slavic Philology at Sofia University "St. Cl. Ohridski ”. The whole scientific activity of Prof. Zaimov is connected with the Institute of Bulgarian Language. The main areas to which his works are dedicated are etymology, onomastics and Old Bulgarian studies. Founder and head of the Onomastics Section and the Group for Publishing Old Bulgarian Monuments at the Institute, while also holding the position of Deputy Chairman of the Unified Center for Language and Literature at the Bulgarian Academy of Sciences. Until 1979, the scientist was a co-author of the Bulgarian Etymological Dictionary, Volumes I and II, whose basic plan and principles, as well as almost the entire first volume, he developed himself. His most famous works on onomastics are: "Local names in the Pirdop region", 1959; "Local names in the Panagyurishte region", 1977, "Settlement of the Bulgarian Slavs on the Balkan Peninsula". Study of Dwelling Names in Bulgarian Toponymy ”, 1967,“ Bulgarian Geographical Names with -jь. Contribution to the Slavic Onomastic Atlas ", 1973," Bulgarian Noun ", 1988," Bulgarian Watercolor "Volumes I and II, 2012, a number of studies on Bulgarian toponymy in Albania and Greece, toponymic word formation and many more. etc. The other main direction of the scientific activity of Prof. Y. Zaimov is the history of the Bulgarian language. Significant achievements in this field are: "Bitola inscription of Ivan Vladislav, Bulgarian autocrat. Old Bulgarian Monument from 1015-16 ", 1970," Suprasalski or Retkov Collection ", 1982-1983, Asemanian Gospel. Old Bulgarian monument from the XI century ”,“ New old Bulgarian monument. May Day inscription from the XI-XII century "1983", "Kichevski triod", 1984/1994. Prof. Zaimov spoke a number of foreign languages. He was a member of the International Onomastics Committee; of the Commission on Onomastics at the International Committee of Slavists; also a member of the editorial board of the Balkan Linguistics magazine. Prof. Zaimov received the Cyril and Methodius Award in 1971 and in 1983 for two remarkable works. For his overall significant scientific activity he is a holder of the Order of Cyril and Methodius I degree and the medal "100 years of BAS".