Availability
In reliability theory and reliability engineering, the term availability has the following meanings:
The degree to which a system, subsystem or equipment is in a specified operable and committable state at the start of a mission, when the mission is called for at an unknown, i.e. a random, time. Simply put, availability is the proportion of time a system is in a functioning condition. This is often described as a mission capable rate. Mathematically, this is expressed as 100% minus unavailability.
The ratio of (a) the total time a functional unit is capable of being used during a given interval to (b) the length of the interval.
For example, a unit that is capable of being used 100 hours per week (168 hours) would have an availability of 100/168. However, typical availability values are specified in decimal (such as 0.9998). In high availability applications, a metric known as nines, corresponding to the number of nines following the decimal point, is used. With this convention, “five nines” equals 0.99999 (or 99.999%) availability.
Availability (noun)
The quality of being available.
“What is your availability this week?”
Availability (noun)
That which is available.
“We have several availabilities.”
Disponibility (noun)
availability
Availability (noun)
the quality of being able to be used or obtained
“turkey producers had been losing sales because of the all-year-round availability of beef”
“the availability of social housing varies widely in rural areas”
Availability (noun)
the state of being otherwise unoccupied; freedom to do something
“they enquired as to my availability for a game the following evening”
Availability (noun)
the state of not being currently involved in a sexual or romantic relationship
“if you call yourself ‘Miss’ you’re advertising your availability to any man who takes a fancy”