Turned something back on or made it active again after it had been stopped or inactive; to restore something to working order.
From 're-' (again) plus 'activate' (to make active), which comes from Latin 'activus'; modern usage common in technology, medicine, and military contexts when restarting dormant systems.
Viruses love this word—herpes and shingles viruses hide dormant in your nerve cells for years, and doctors call it 'reactivation' when they suddenly wake up and cause symptoms again, which is why these infections can come back unexpectedly.
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