The research reported in this paper explores Manuel Rodríguez-Navas's Diccionario general y técnico hispanoamericano (1918). It is an update of another dictionary previously published by this author: Diccionario completo de la lengua española (1905). The change in title has to do with the new entries in the dictionary, mainly scientific terms and American usage of words. The paper discusses the innovations announced in the foreword, especially the "inclusion of prefixes, infixes, suffixes, roots and endings as part of the general vocabulary of the Spanish language." According to Rodríguez-Navas (1918:4), these elements are necessary "to understand a chemical formula, translate a neologism or trace the history of a word." The analysis focuses on both the dictionary's macrostructure (and how it evolved out of the earlier version) and the microstructure of the new entries. [ABSTRACT FROM AUTHOR]