What is Marketing Communications?

Legal Definition
Marketing communications (MC) uses different marketing channels and tools in combination: Marketing communication channels focuses on any way a business communicates a message to its desired market, or the market in general. A marketing communication tool can be anything from: advertising, personal selling, direct marketing, sponsorship, communication, promotion and public relations.

MC are made up of the marketing mix which is made up of the 4P's: Price, Promotion, Place and Product, for a business selling goods, and made up of the 7P's: Price, Promotion, Place, Product, People, Physical evidence and Process, for a service based business.
-- Wikipedia
Legal Definition
Print, radio, television, direct mail, and personal selling as one or more channels of delivering coordinated promotional messages.