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antes (Adverb) "before"
12th cent. In the Middle Ages antes and ante were used side-by-side. Between the two, ante is the original form. Adverbial -s was added via analogy with other adverbs. A similar addition was made in quizá. See ante.
Modern Spanish uses antes in a temporal sense and relegates ante to particular contexts.
Indo-European
Romance
Asturian antes, Portuguese antes, Galician antes
Basque
Lapurdian aintzin "front," Roncalese antzin 'id.,' Zuberoan aitzin 'id.,' borrowed from a dialect in Proto-Romance

Anzes appears in both the Glosas Emilianenses (11th cent.) and the Glosas Silenses (11th cent.) as a gloss for Latin prius "before." This variant in either Old Spanish or Old Aragonese was probably close to what was borrowed by Basque. See Trask (2008).