The story
Etymology from Wiktionary, CC BY-SA 4.0.
Today it means: An SI unit of power equal to 10¹⁵ watts. Symbol: PW. An amount of power much larger than all the power generated by all power stations on Earth. (Consuming 1 petawatt during a duration of 1 hour would consume 1 petawatt-hour of energy.) Full definition →
Etymology from Wiktionary, CC BY-SA 4.0.