The story
From ergo- + -sphere. Coined by Remo Ruffini and John Archibald Wheeler in 1971 in reference to the fact that it is theoretically possible to extract energy from the region.
Etymology from Wiktionary, CC BY-SA 4.0.
ergosphere
Today it means: A region outside the event horizon of a rotating black hole in which space and time are distorted by shear forces. Full definition →