Wiktionary
n. A votive picture displayed above and behind the altar in a church.
Wikipedia
A retablo in Mexican folk art (also lámina) is a devotional painting, especially a small popular or folk art one using iconography derived from traditional Catholic church art. In Spain and other Spanish speaking countries and the Philippines the word is used in the original, different though related sense, where retablo is equivalent to reredos in English or retable in French. It means a decorated vertical structure rising behind the altar of a church, typically including painting, sculpture or combination of the two, and an elaborate framework enclosing it. The Latin etymology of this Spanish word means "board behind". Aside from being found behind the altar, "similar ornamental structures are built and carved over facades and doorways" (Fernandez 23), called overdoors.
Small retablos are devotional or votive paintings, often on rectangular sheets of tin that illustrate holy images such as Christ, the Virgin Mother, or one of the hundreds of saints. Many are ex-votos ("from a vow") that depict the story that led to their commission, usually dangerous or threatening events that actually occurred, and which the person survived, thanks to the intercession of a sacred person - God, Mary or a saint. They are made as a way of thanking the sacred person for protection in precarious situations, such as surviving an illness or earthquake. This class of ex-votos often shows the protected humans in the dangerous situation, and the sacred person who protected them, usually with an inscribed explanation of the events, with the date and location. Both devotional and especially ex-voto retablos may be deposited at a shrine as a votive offering, or alternatively kept at home.
Reredos of the Late Middle Ages and Renaissance in Spain grew extremely large and elaborate, typically using carved and gilded wood, and rising as high as 40 feet or more. The tradition of making them was taken to the new Spanish Empire in America. There, by the late 18th century at least, the word became used for much smaller popular religious paintings, both conventional devotional images and ex-votos (paintings giving thanks for protection through a specific episode). These were typically made to express gratitude towards the Virgin Mary for saving a person or a loved one from a nearly fatal event.
Usage examples of "retablo".
On the 24th of June every year the magnificent retablo in massive silver, which is preserved among the treasures in the Opera del Duomo, is displayed in the Baptistery.
Their house, a kind of southwestern religious Smithsonian Institution, was crammed full of bultos and retablos, carved saints and painted saints, bleeding saints and saints wearing little cloth capes on which roses and moons and stars were embroidered, and saints carrying silk shoulder pouches, and saints with angels driving their plows through the earth behind them, and saints with gourds full of sacred water and baskets overbrimming with sacred bread--they had santos in their household like most of Milagro's dogs had fleas!