Definition of aftermarkets:
(n) :
(business) The market for further goods and services, such as replacement parts and accessories, subsequent to the sale of a product such as an automobile or computer.
(n) :
(business) The industry that serves that market.
(n) :
(finance) Trading activity in a security immediately following its initial offering to the public.
(v) :
(business) To sell goods or services in the aftermarket.