C corporation definition. Analyzing the definition of key term often provides more insight about concepts. C Corporation can be defined as: Corporation that does not qualify for nor elect to be treated as a proprietorship or partnership for income tax purposes and therefore is subject to income taxes; also called C corp. A C Corporation is the default setting for an organization that incorporates. A C corporation can be contrasted to pass through entities like an S corporation or LLC. A C corporation has liability protect but is subject to double taxation. An S corporation or LLC is designed, in part, to keep the liability protection and eliminate the double taxation.