Tesoro de la lengua castellana o española

[1] Covarrubias's stated intention was to develop an etymological dictionary to trace the origins of Castilian, modeled on the Etymologiae by Isidore of Seville, who had done the same for Latin.

Covarrubias was also aware of contemporary work in lexicography from other countries, including Jean Pallet's Dictionnaire très ample de la langue espagnole et françoise [Very Copious Dictionary of the Spanish and French Language] (Paris, 1604) and Jean Nicot's Trésor de la langue français [Treasury of the French Language] (Paris, 1606).

He aimed to give foreigners a sense of the propriety and elegance of the Spanish language, to the honor of the Spanish nation ("dar noticia a los extranjeros del lenguaje español, y de su propiedad y elegancia, que es muy gran honor de la nación española").

The book takes a broad view of the lexicon, including regionalisms (especially from Old Castile, Toledo, and Andalusia), slang, jargon, and archaisms.

Encyclopedic information includes explanations of the object to which the word refers, issues relating to symbolism, texts that illustrate the topic, moral judgments, and trivia.

Noydens' volume added 326 new entries, consisting mainly of encyclopedic information taken from the Glosario de voces oscuras [Glossary of Obscure Voices] by Alejo Venegas.

Covarrubias achieved greater recognition after the founding of the Real Academia Española [Royal Spanish Academy] in 1713.

In the preface to the Diccionario de autoridades the academy recognizes Covarrubias' work as a predecessor in the scholarly canon.