1. redouble, escalate, intensify, step up

usage: double in magnitude, extent, or intensity; "The enemy redoubled their screaming on the radio"

2. redouble, double, duplicate

usage: double again; "The noise doubled and redoubled"

3. redouble, intensify, deepen

usage: make twice as great or intense; "The screaming redoubled"

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See also: redouble (Dictionary)