Jessie Payne Margoliouth, who was responsible for the widely used English abridgment of her father’s massive Thesaurus Syriacus, here includes additional material for the Thesaurus, based on three decades of Syriac study after the publication of the original lexicon. Robert Payne Smith had himself collected some material for the purpose of a supplement, and his daughter was aided by several scholars in compiling the work, which includes a large number of new words or meanings (with citations); proper names are also listed. Differences from the Thesaurus itself are that the definitions are given in English (not Latin), and that Christian Palestinian Aramaic and neo-Aramaic varieties are excluded. The work concludes with a short list of addenda and corrigenda.