The act of making something more solid, stable, or determined; becoming or causing to become firm.
Present participle of 'firm,' derived from Latin firmus. In both historical and modern usage, this gerund form describes the ongoing process of solidification or strengthening.
In skincare marketing, 'firming' became a buzzword in the 1980s-90s, but the word actually describes any physical process of becoming more compact—from concrete setting to muscles toning to resolve hardening.
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