非常
ひじょう · hijou · JLPT N3 · noun
emergency
🚨 非常 = 非 not + 常 ordinary: not ordinary, so extraordinary or an emergency
非 means not or un-, as in 非公式 (unofficial). 常 means usual, as in 日常 (daily life). Something that isn't usual is extraordinary, and that is why 非常口 (not-usual exit) is the emergency exit. As an adverb, 非常に means very.
非 — two opposing wings 羽-like form
Originally a pictograph showing two wings spread in opposite directions, symbolizing things facing away from each other. From this 'opposition' image came the meaning 'not' or 'wrong.' It is also used as a phonetic component in many characters like 排, 悲, and 罪.
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.