From tender +‎ -dero.

tendedero m (plural tendederos)

1. clotheshorse, drying rack (device or place on which laundry is hung out to dry)

   Synonyms: tenderete, tendedor, (Latin America) ténder

2. (rare) clotheslines

   Synonyms: tendal, cuerda para tender la ropa

• “tendedero”, in Diccionario de la lengua española [Dictionary of the Spanish Language] (in Spanish), online version 23.8.1, Royal Spanish Academy [Spanish: Real Academia Española], 15 December 2025