the amount of something (as whiskey or oil) lost in storage or transportation
"The new pipeline suffered a massive outage, causing thousands of gallons of crude oil to evaporate before reaching the refinery."
a temporary suspension of operation (as of computers)
"there will be a network outage from 8 to 10 a.m."
A temporary suspension of operation, especially of electrical power supply.
"The sudden blackout left the entire neighborhood in darkness after a brief but frustrating outage hit the grid at midnight."
Outage comes from combining the word out with the suffix -age, following the same pattern as shortage. It originally meant a state of being out or absent.