The word "毛毛" is formed through the morphological process of reduplication, where the single-syllable noun "毛" (máo), meaning "hair" or "feather," is repeated. This repetition transforms the concrete noun into a colloquial and often affectionate term that conveys a sense of smallness, fuzziness, or a downy texture. It frequently refers to fine body hair, peach fuzz, or the soft fur of a young animal, and can also be used as a childish or endearing word for "hair" in general. The reduplication itself softens the word, adding a qualitative and diminutive nuance that the single character does not possess.