Faced with threats, the old man stood unyielding and gave no ground.
Tips
memory
铮铮 (zhēngzhēng) is the onomatopoeia of metal clanging — picture iron bones (铁骨) ringing like a struck blade. The reduplication makes the image vivid and the praise emphatic.
usage
Almost always praise applied to a person's moral fiber: martyrs, principled officials, refusers-to-bend. Never used for physical strength.