lightning-quick

The compound "lightning-quick" is a modern metaphorical formation, drawing on the immense speed of a natural phenomenon to intensify a basic adjective. The first element, "lightning," originates from the Old English concept of illumination, its association with swiftness emerging from the observable, instantaneous flash. The second element, "quick," has a profound journey from its Proto-Indo-European root meaning "alive," through Old English "cwic" (living), to its Middle English specialization into "rapid," capturing the essence of lively motion. Thus, the compound logically builds its meaning by comparing a subject's speed to the proverbial and instantaneous velocity of lightning, transforming an ancient word for "life" into a benchmark for extreme rapidity.

Structure: lightning (noun) + quick (adjective) - lightning: From Middle English lightning, lightening, from Old English līhting, from the verb līhtan ("to lighten, illuminate"). The modern spelling with 'n' solidified in the 16th century. It functions as a noun used attributively to modify the adjective 'quick'. - quick: From Middle English quik, from Old English cwic ("alive, living, animate"), from Proto-Germanic kwikwaz, from Proto-Indo-European gʷih₃wós ("alive"). The semantic shift from "alive" to "fast, rapid" occurred in Middle English, influenced by the notion of lively movement.