APIs are a very abstract digital concept, loosely wrapping a variety of text, documentation, artifacts, and code that define what an API is capable of doing. A thoughtful API life cycle begins by sitting down with all stakeholders and finding a common way of defining each API and how it will move forward over time.
A well-executed definition of the API life cycle lays the important groundwork that will contribute to its usability. You are providing the API the nutrients it needs to operate. The definition stage may seem like an easy one to skip, but in reality, it is the most important place to begin, laying the foundation for almost every other stop along the way and contributing to velocity.