The massive Syriac-Syriac/Arabic lexicon—actually more an encyclopedia than a mere lexicon—of Bar Bahlul (10th century) is one of two commonly cited Syriac dictionaries from the medieval period, the other being that of Bar Ali. The work includes Syriac words as well as Greek words met in Syriac literature, sometimes with copious explanations. Bar Bahlul, who probably composed his work in Baghdad, used a wide variety of sources, both Syriac and Arabic, in compiling the lexicon. The first two volumes contain the lexicon itself with a critical apparatus, while the third volume has important introductory material, indices, and a list of corrections and additions. The introduction touches on the thirteen manuscripts from which the work was edited and provides the abbreviations used by Bar Bahlul, the author’s life, Latin translations of the Syriac and Arabic prefaces, a detailed list of sources Bar Bahlul used, and a list (and index) of the Aramaic dialects that he cites in the lexicon. The indices are for Syriac and Hebrew, Arabic, Persian, Greek, and biblical passages cited. Advanced Syriac scholars and Semitic lexicographers will find the work indispensable.