平気
へいき · heiki · JLPT N2 · na-adj
unconcern
平 = level/flat + 気 = mood: a mood kept level, so nothing ruffles it = calm
平 means level or flat, and 気 means mood or spirit. A mood that stays level is unbothered, so 平気 means calm, composed, or unconcerned, as in I'm fine.
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.'