This article focuses on compound nouns and adjectives in the first dictionary by K. Sirvydis Promptuarium dictionum Polonicarum, Latinarum et Lituanicarum. The analysed compounds are firstly divided into groups according to the part of speech the constituents of the compound belong to, seeking to identify the most productive model of compounds in this 17th-century source. Moreover, attention is also paid to the relationship between elements of compound words and to rare compound words of indirect meaning. Finally, the use of Lithuanian compounds is compared to neighbouring Polish words, to clarify if Sirvydas tended to use mechanical translation.