The word "半辈子" is formed by directly combining the concept of "半" (half) with the concept of "辈子" (a lifetime or lifespan). It creates a single, concrete unit of meaning by visually and metaphorically slicing the entirety of one's lived experience into two equal parts, evoking the image of a complete journey from birth to death and then focusing on one substantial portion of it. This formation relies on an intuitive, almost spatial understanding of time as a measurable whole that can be divided, resulting in a term that captures a profound duration of personal history in a single, graspable idea.