The word "一辈子" is formed through a vivid, metaphorical construction where the character "一" (one) is combined with "辈" (which means generation or lifetime) and the nominal suffix "子" to create a single, cohesive concept. It literally pictures "one generation", but this image is used not to count dynasties or family lines, but to metaphorically represent the complete and unbroken span of a single human life from birth to death, as if that entire journey were contained within the frame of a single generational cycle.