Other forms: bestsellers
A bestseller is the book everyone is buying this year. A runaway bestseller, the bestseller list, an international bestseller.
It is a measure of sales rather than quality, and the lists that certify it are compiled differently — some by copies sold, some by sampled shops, and the differences produce real arguments. Getting onto one drives further sales, which is most of why publishers care. Note bestselling as the adjective; and that a bestseller need not have sold very many at all in a quiet year.
1nounbestsellerA book that sells in very large numbers.
“Her first novel became a bestseller, and she gave up her job to write full-time.”
bestseller is a commercially successful book.
Also accepted in games: best seller
Best plus seller, from American English about 1889. Seller here means the thing sold rather than the person selling it, which is an unusual use.
From best + seller.
Etymology from Wiktionary, CC BY-SA