衡

It is a phono-semantic compound

角 (“horn”) + 大 (“big”) combine to form the semantic element depicting a crossbar or horizontal object;

行 (“to go, to move”) provides the phonetic value.

Over time, through clerical script (隸書 lìshū) and regular script (楷書 kǎishū), the lower part of 角 was truncated, making it resemble the upper portion of 魚 (“fish”). When this abbreviated form was joined with 大, it produced a shape nearly identical to an alternate form of 魚. Indeed, in historical manuscripts, the left component of 衡 was sometimes written as 鱼/魚, creating interchangeable variant forms.

衡 retains its core imagery of a balance beam or crossbar, extending metaphorically to ideas of equilibrium, measurement, and horizontality in East Asian languages.

In modern Korean, 형 (衡) appears in words connected with measurement, balance, and horizontal direction:

균형 (均衡) – balance, equilibrium

평형 (平衡) – balance, symmetry

수평 (水平, but 平衡 used for balance in physics/abstract sense)

횡형 (橫衡) – crossbar, horizontal alignment

衡 is sometimes used as a synonym or interchangeable character for 橫 (횡, “horizontal, across”).