Wiktionary
n. 1 (context music English) A genre of Mexican music based on the polka, depicting drug smugglers, cartels, and other criminal activities. 2 (context music English) Any song in this genre.
Wikipedia
A narco-corrido (, Drug Ballad) is a subgenre of the Mexican norteño- corrido (northern ballad) music genre, a traditional folk music from northern Mexico, from which several other genres have evolved. This type of music is heard on both sides of the US–Mexican border. Besides from being heard in Mexico, it is widely heard and produced throughout all Latin America. It uses a danceable, accordion-based polka as a rhythmic base. The first corridos that focus on drug smugglers—the narco comes from " narcotics"—have been dated by Juan Ramírez-Pimienta to the 1930s. Early corridos (non-narco) go back as far to the Mexican Revolution of 1910, telling the stories of revolutionary fighters. Music critics have also compared narcocorrido lyrics and style to gangster rap and mafioso rap.
Narcocorrido lyrics refer to particular events and include real dates and places. The lyrics tend to speak approvingly of illegal activities, mainly drug trafficking.