Wiktionary
n. (context uncountable English) Mandarin popular music.
Wikipedia
Mandopop refers to Mandarin popular music. The English term was coined around 1980 soon after " Cantopop" became a popular term for describing popular songs in Cantonese; "Mandopop" was used to describe Mandarin-language popular songs of that time, some of which were versions of Cantopop songs sung by the same singers with different lyrics to suit the different rhyme and tonal patterns of Mandarin. It is now used as a general term to describe popular songs performed in Mandarin.
Mandopop is categorized as a subgenre of commercial Chinese-language music within C-pop. Mandopop was the first variety of popular music in Chinese to establish itself as a viable industry. It originated in Shanghai, and later Hong Kong, Taipei and Beijing also emerged as important centers of the Mandopop music industry. Among the countries where Mandopop is most popular are mainland China, Hong Kong, Taiwan, Malaysia, and Singapore.