平常
へいじょう · heijou · JLPT N1 · na-adj
normal
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.'
常 — 巾 (cloth) + 尚 (phonetic, 'esteem')
Originally written 裳, 常 was a phono-semantic compound: 巾 ('cloth') gave the meaning and 尚 supplied the sound, referring to a long lower garment or skirt. Over time the meaning shifted from 'everyday garment' to 'ordinary, regular, constant', while 裳 took over the original clothing sense.