This work traces the etymologies of the entries to their earliest sources, shows their kinship to both Spanish and English, and organizes them into families of words in an Appendix of Indo-European roots. Entries are based on those of the Diccionario de la lengua española de la Real Academia Española.

Written from the twin perspectives of linguistic and cultural change, this pioneering book describes the language inherited from Latin and how it was then influenced by the Visigothic and Arabic invasions and later by contact with Old French, Old Provençal, English and, not least, with the indigenous languages of South and Central America.