正せい中ちゅう線せんせいちゅうせんMeanings1nounmedian line; midlineUsed in anatomy, geometry, and technical contexts to refer to a line that divides something into left and right halves.人じん体たいの正せい中ちゅう線せんは、左さ右ゆう対たい称しょうの基き準じゅんとなる