The state of a system able to do what it is for — wholeness in function. Spoken of servers and selves alike in this house, and tended in both.
Old English haelth (wholeness, being whole, soundness), from hal (whole); wholeness of function, spoken of servers and of selves alike.
One word carries both a server's uptime and a person's own condition, because both ask the same question: can the thing still do what it exists for, right now.