From Longman Dictionary of Contemporary Englishdot-comdot-com, dot.com, dot com /ˌdɒt ˈkɒm $ ˌdɑːt ˈkɑːm/ adjective [only before noun] informal relating to a person or company whose business is done using the Internet or involves the Internet a dot-com company dot-com millionaires —dot-com noun [countable] Several of the leading dot-coms saw their share prices slide yesterday.From Longman Business Dictionarydot-comdot-com /dɒtˈkɒmdɑːtˈkɑm/ (also dotcom), dot.com noun [countable] COMPUTING a company that does business using the Internet or provides a service on the InternetMany dotcoms tried to build a global brand before their business model even worked. —dot-com adjective [only before a noun]The Nasdaq hit its high in March, 2000, and within a few years most of the dot-com sector was wiped out.