A fierce and formidable person or thing, often one who appears harmless but is truly dangerous or powerful; a tough individual or a big shot.
他平时看起来不声不响，但在谈判桌上可真是个没毛大虫，让对手们都感到压力。
He usually appears quiet and reserved, but at the negotiation table, he's truly a formidable force, putting pressure on all his opponents.
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