Origin

This character combines the moon radical (月) with a horizontal line (一) to suggest something that continues or persists. The moon appears regularly in the sky night after night, making it a natural symbol for repetition and continuation. When you add the line element suggesting "one" or "singular continuity," the combined image conveys the idea of something that keeps happening or adding up—hence "moreover" and "also," meanings that suggest accumulation or additional points. Over time, the visual connection faded and the character became a written convention for these conjunctive meanings rather than something you'd recognize as moon-related by looking at it.