水平線
すいへいせん · suiheisen · JLPT N2 · noun
horizon
🌊 水平 = level + 線 = line: the level line where sky meets sea or land
水平 (suiheい) means level or flat, and 線 (sen) means line. Together they name the flat line where the sky appears to meet the sea or land.
水 — pictograph of flowing water
水 is a pictograph depicting a stream of flowing water, with the central line representing the main current and the side strokes showing splashing droplets or ripples. In oracle bone script it was drawn even more clearly as a wavy vertical line with branches. It retains its original meaning of 'water' and also serves as a radical, often appearing in the compressed form 氵.
平 — horizontal stroke 一 + 干 with two dots 八
平 originally depicted a balance or scale being level, suggesting evenness. The horizontal lines and symmetrical dots evoke a flat, balanced surface. Over time it extended from 'level/flat' to broader senses like 'calm,' 'peaceful,' and 'ordinary.'