The word 婆婆 is formed through the linguistic process of reduplication, where the single character 婆 (pó), which broadly means "old woman" or "matron", is duplicated. In Chinese, reduplication often serves to create familiarity, indicate endearment, or specify a particular relational term. In this case, the base meaning evolves; while 婆 alone can refer to an elderly female, the reduplicated form 婆婆 specifically means "husband's mother" (mother-in-law) or, in some contexts, "grandmother" (paternal), demonstrating how repetition can crystallize a more precise and intimate familial role from a more general root word.