Availability is the ability to be accessed or used. ACCESS (6 letters) is the ability to gain entry or use something, SEASON (6 letters) is a period of time with specific characteristics, ACCESSIBILITY (13 letters) is the quality of being able to be reached or entered, and uptime (6 letters) is the amount of time a system or machine is operational. Availability is the combination of these factors, allowing something to be accessed or used at any given time.