Dave McClure - A startup is a company that is confused about, what its product is, who its customers are, how to make money. As soon as it figures out all 3 things, it ceases being a startup and becomes a real business. source
Steve Blank - A startup is a temporary organization used to search for a repeatable and scalable business model. source
Eric Ries - A startup is a human institution designed to deliver a new product or service under conditions of extreme uncertainty. source
In general parlance, bootstrapping usually refers to the starting of a self-sustaining process that is supposed to proceed without external input. In computer technology the term (usually shortened to booting) usually refers to the process of loading the basic software into the memory of a computer after power-on or general reset, especially the operating system which will then take care of loading other software as needed. source
A manifesto is a published verbal declaration of the intentions, motives, or views of the issuer, be it an individual, group, political party or government. A manifesto usually accepts a previously published opinion or public consensus and/or promotes a new idea with prescriptive notions for carrying out changes the author believes should be made. It often is political or artistic in nature, but may present an individual's life stance. source
A minimum viable product has just those core features that allow the product to be deployed, and no more. The product is typically deployed to a subset of possible customers, such as early adopters that are thought to be more forgiving, more likely to give feedback, and able to grasp a product vision from an early prototype or marketing information. source
Steve Blank: "You’re selling the vision and delivering the minimum feature set to visionaries, not everyone."