best seller ˌbest ˈseller , best-seller noun [countable] MARKETING
a very popular book or other product, that many people buy:

• The book has been on the New York Times fiction best-seller list for more than 30 weeks.

• The company's best sellers are its biotechnology drugs.

— best-selling adjective [only before a noun] :

• America's best-selling pickup truck

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best-selling UK US (also bestselling) /ˌbesˈselɪŋ/ adjective [before noun] COMMERCE
extremely popular and selling in very large numbers: »

the best-selling brand in the country


a best-selling book/game/phone

producing books, songs, etc. that are extremely popular and have sold in large quantities: »

a best-selling author/artist

Financial and business terms. 2012.