The article discusses the importance of terms in subject- matter conversation. The issue of architecture as being the crossing of science and art is reminded of. Eponymous terms are defined. The opinion is held that such a term which is a person’s name, the name of a city, village, of some other geographical place, of a country or nation, as well as of a tribe included in its structure, can be called an eponymous term. The Lithuanian terms of such a  kind were not discussed till now, that’s why the article could give the start for discussions or for  more thorough studies in this field. Logical – semantic links between the eponymous term and its original source (the proper name) are examined. As one-word terms are loans, or borrowings, their original source is indicated. A lot of material is presented, and it could help to determine and identify the main ways of the formation of eponymous terms as well as their structural patterns. The given patterns could be successfully applied in forming the terms of other special fields.