軌道
きどう · kidou · JLPT N1 · noun
orbit
🪐🛤️ 軌道 = 軌 (rail) + 道 (road): a fixed path, like train rails or an orbit
Rails guide a train along one fixed route, and a planet's orbit follows the same idea: a set path around a star. Both meanings share the 軌 (rail) character.
道 — 辶 (walk) + 首 (head)
Originally a compound of 辶 'walk/movement' and 首 'head', depicting a path one walks while looking ahead. The literal sense 'road, way' extended metaphorically to 'method, doctrine, the Way (Dao)'. This philosophical meaning became central in Daoist and Confucian thought.