Everyday users are confronted with increasingly complex technologies, be that novel introductions or ever-changing and expanding familiar interfaces. This creates the challenge of users needing to perpetually discover new functionality and interactivity, which is rarely addressed when novel technology is proposed. A possible contributing factor for this, is the variety of, often inconsistently defined, associated concepts and a consequent lack of clarity on how to address these problems. We examine usage and definitions of discoverability as well as related concepts and offer clarifications where definitions are ambiguous while highlighting focus areas and limitations. In doing so, we provide a clear definition of discoverability, underscore the separation of system, feature and interaction discoverability and elucidate how other concepts focused on initial interactions differ.