The term "white-knuckle" is a vivid compound adjective originating in mid-20th century American English. It derives from the literal physiological reaction of gripping something so tightly in fear or intense excitement that the blood drains from the knuckles, causing them to appear white. This concrete image was first applied to describe terrifying amusement park rides and later extended to any experience inducing similar high-stress tension, such as a turbulent flight or a suspenseful situation. The logic perfectly captures the cause-and-effect link between extreme emotional arousal and its visible physical symptom, evolving from a descriptive phrase into a fixed lexical item.

Structure: white (color) + knuckle (finger joint) - white: From Old English hwīt, meaning the color white. In this compound, it describes the physical appearance. - knuckle: From Middle English knokel, meaning a joint of a finger. In this compound, it refers to the part of the body affected.