The word 一直 is formed through the complementary fusion of two characters, each contributing a core spatial concept that together create an abstract idea of continuity. The first character, 一 (yī), means "one" or "single", establishing a notion of singularity and lack of division. It is combined with 直 (zhí), which originally depicted a straight, un-deviating line, as seen in its ancient pictograph of an eye looking straight ahead. Thus, the compound visually and conceptually paints the picture of "a single straight line", which was then extended metaphorically from the physical realm into the domains of time and action to mean "continuously", "straight", or "all along", representing an unbroken, direct, and persistent course.