el dorso - back side of something, backSpanish example: En el billete de 20 pesos, al dorso aparece la imagen de un guajiro.
English example: On a 20-peso bill, on the back appears the image of a peasant.
Source: el dorso - back side of something, back (https://www.123teachme.com/spanish_feeds/word_of_the_day/2022/2/1)