The word 姨妈 is formed by combining two characters: 姨, which means "maternal aunt", and 妈, which means "mother". It is a compound term that specifically denotes "mother's sister", where the repetition of the maternal concept (姨 already implying a maternal relation) is reinforced by 妈 to highlight the close, mother-like role and seniority of this particular aunt within the traditional Chinese kinship system, creating a distinct and familiar term for this family member.