Origin: Germanic Old English prefix
Bestseller has 2 different meanings across 1 category:
a book that has had a large and rapid sale
"After releasing her new novel, the author watched in awe as it climbed the charts to become an instant bestseller within days of hitting store shelves."
A book or other product that has sold in large numbers.
"After months of waiting, I finally got my hands on a copy of the new thriller bestseller that everyone is talking about."