Definition of the word conk out

The phrase "conk out" originated in the early 20th century, particularly in the context of automobile racing. It referred to the sudden stopping or breakdown of a car's engine due to exhaustion or overheating. Specifically, "conk" derives from the shortened form of the verb "conkiverse," which means "to yield, give way, or break down" in old English. In the context of vehicles, "conk out" began to be used as a synonym for "stall" or "die" in regards to an engine failing to function. Over time, the phrase came to be applied more broadly as a colloquial expression for collapsing or falling asleep suddenly, as the metaphor of an engine breaking down resonated with the unexpectedness and suddenness of falling asleep.