猛然
měng rán · HSK 7
suddenly
💥 猛 fierce/violent + 然 (adverb suffix -ly) = in a violent burst, i.e. suddenly
猛 carries the sense of fierce, abrupt force (same 猛 as in 猛烈 fierce); 然 is the classic adverb-forming suffix turning it into an -ly word. Together: it happens with violent quickness, all at once.
猛 — dog radical 犭 + 孟 (mèng, phonetic)
猛 is a semantic-phonetic compound. The dog radical 犭 indicates a fierce animal, while 孟 (mèng) supplies the sound. Originally describing a ferocious hunting dog, its meaning broadened to 'fierce, violent, vigorous' for anything intense.