†1. intransitive. To engage in work or activity; to be in active operation; to exercise one's faculties or powers. Obsolete.
2. transitive. To rouse into activity; to put to work or effect; to exercise. Also: to give effectiveness to; to endow with the capacity to do something; to empower. Now rare except as in sense 4a.
3. transitive. Physics. To increase the energy of (a body or system); (in later use) esp. to impart energy to (matter, esp. a particle); to cause (a particle) to move into a higher energy state.
a. transitive. To supply (a device, machine, etc.) with energy, esp. in the form of electricity; to cause (a device, machine, etc.) to begin operating by doing this; to power up; to activate.
b. intransitive. Of a device, machine, etc.: to acquire the energy required for operation; to become energized (energized adj. 3).
5. transitive. To infuse, fill, or supply with vigour, dynamism, or enthusiasm; to invigorate, to vitalize; to stimulate.
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