The word "兜兜" is formed through the linguistic process of reduplication, where the single-character noun "兜" (dōu), which originally means a pocket, pouch, or the act of wrapping/carrying something, is repeated to create a new, often more informal or affectionate term. This reduplication softens the word, making it sound more intimate and childlike. In this specific case, "兜兜" commonly refers to a bib for a baby or toddler, effectively transforming the concept of a functional "pocket" or "container" into a cute, protective garment that "catches" food, showcasing how reduplication can shift both meaning and emotional tone.