a style of calligraphy
籀 refers to a specific historical style of Chinese calligraphy, associated with the ancient Zhou dynasty script. Its meaning is narrowly tied to this calligraphic style.
籀 is composed of 竹 (bamboo) and 㨨, a component that likely contributes phonetic information. The character is historically associated with the Zhou dynasty script style, but the exact origin of the 㨨 component is uncertain.
The bamboo radical 竹 suggests writing materials, and the complex lower part 㨨 resembles a hand holding a brush over a field of characters. Picture ancient scribes using bamboo slips to practice the distinctive Zhou calligraphy style.
For チュウ, imagine a calligrapher named Chu who perfected the Zhou style: Chu -> チュウ, and his brush dances over the bamboo slips.