Other forms: downtimes
Downtime is time when nothing is being made, run or done — the machine is off, the system is down, the work has stopped. An hour lost while the production line waits for a part; a website that goes dark at two in the morning while somebody updates it.
In factories and computing, downtime costs money and gets counted in minutes: scheduled downtime, unplanned downtime, four hours of downtime last month. From there the word moved to people. Your own downtime is the part of the day when nobody wants anything from you — Sunday afternoon, the train home, a week with no plans in it. Both uses sit slightly on the informal side; a formal report will say system availability where a colleague says downtime. Its neat opposite is uptime, the stretch when everything is running.
1noundowntimeTime when a machine or system is not working or not in use.
“The upgrade will mean three hours of downtime on Sunday night.”
2nounspentTime when you are not working, spent resting.
“He gets almost no downtime between the two jobs.”
Too few real examples of this word to estimate which sense is commonest.
downtime is a period of time.
No mystery in the making of it: downtime is down plus time, the time during which something is down. The down here is the down of a stopped machine, not the down of a staircase.
From down + time.
Etymology from Wiktionary, CC BY-SA