
As the first part of a series devoted to common lexicographic issues arising in compiling bilingual learner dictionaries of idioms, the article comprises two sections concentrating on idiom characteristics and idiomatic equivalent selection. Section one elucidates the notion of idiom by providing its definition and discussing its distinctive features along with semantic and syntactic typologies. Section two, in turn, demonstrates the process of selecting Polish equivalents for English weather idioms by carrying out an illustrative analysis of the semantic, syntactic, and pragmatic properties of four idioms. The methodology presented in this work incorporates some elements from Szczepaniak and Adamska-Sałaciak’s (2010) study, which involves the functionally oriented methodological framework developed by Dobrovol’skij and Piirainen (2005). An analogous procedure identified 30 Polish idiomatic equivalents for a total of 34 English idioms, whose lexicographic representation is illustrated in the second part of the series.