ˌbest-ˈsel ‧ ler BrE AmE , best‧sell‧er /ˌbestˈselə $ -ər/ noun [countable]
a popular product, especially a book, that many people buy:
His new book went straight to number one on the best-seller list.
The game is already a bestseller in Japan.
—best-selling adjective [only before noun] :
a best-selling author
the UK’s best-selling album