makes something more snug, secure, or firmly fixed; or makes rules, control, or money supply more strict and controlled.
From Old English 'tiht' meaning 'pull,' combined with '-en' suffix to create a verb. The sense of 'making strict' evolved metaphorically from physical tightening.
The Federal Reserve uses 'tightening' of the money supply to fight inflation—they literally control how tight money flows through the economy using mathematical models.
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