Sebastián de Covarrubias, Tesoro de la lengua castellana o española (Madrid, 1611)

The folio dictionary printed at Madrid by Luis Sanchez in 1611 in which Castilian is explained in Castilian, with an etymology attached to almost every headword. Covarrubias worked alone, named the living Arabic scholars he leaned on, alphabetised by sound rather than by spelling, and warned his reader that some etymologies he prints are false ones he recorded because they were current. Arabic had reached his alphabet; at the opening checked here, the American loan-words had not.