The word "默默" is formed through the morphological process of reduplication, where the single character **默** (mò), meaning "silent" or "quiet," is duplicated to create a disyllabic adverb. This repetition serves to intensify and emphasize the base meaning, transforming it from a simple state of silence into a manner of action—specifically, doing something quietly, persistently, and without drawing attention, as in working "tirelessly and quietly" (默默工作) or enduring "in silence" (默默承受).