Hard, cold, and unyielding like steel; often describing someone's harsh, determined expression or attitude.
From 'steel' (the metal) plus the suffix '-y' meaning 'having the quality of'. The word draws on steel's properties of hardness and strength to describe emotional and physical hardness.
A steely gaze or steely determination compares human emotions to the hardest metal—it's why we use metal words for toughness, because steel doesn't bend, and neither will that person!
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