Abstract: This study aims at interpreting the lexical means for intellectualization and the terminology in a part of Диплографiя или какъ ся дрьжять търговскы книгы (Diplography or how to keep the books) by Stoyan and Hristo Karaminkovi (1850), entitled Book of letters. The vocabulary is considered from a word-formation aspect, as well as from the perspective of its origin. The terminological units are defined in four groups: those that are used to this day; terms that are outdated in form but not in meaning; terms named today with new words; terms naming concepts from the field of commerce and accounting that no longer exist. Besides, they are considered part of idiomatic expressions. A minimum number of foreign vocabulary is established, which is of two types: international and Oriental (naming units of measurement).
Key words: book of letters, lexicology, trade and accounting terminology