means A device that converts direct current (DC) into alternating current (AC), letting battery or solar power run ordinary household appliances.

from From the Latin 'invertere,' 'to turn upside down' (in-, 'in/upon,' plus 'vertere,' 'to turn' — the same 'vertere' that gives us 'reverse' and 'version'). English 'invert' arrived in the 1500s for any turning-over or reversing; the electrical 'inverter' is a much later technical coinage, naming the box that flips current's character from steady DC into the back-and-forth swing of AC.