The word 细胞 (xìbāo), meaning "cell" in the biological sense, is formed by combining two meaningful characters to create a direct and vivid metaphor. The first character, 细 (xì), means "fine", "small", or "minute". The second, 胞 (bāo), originally means "womb", "afterbirth", or, by extension, any enclosing membrane or sac. Thus, the compound visually conceptualizes a biological cell as a "small sac" or "tiny enclosed unit", perfectly capturing the essential idea of a microscopic, membrane-bound structure fundamental to life.