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1. Put in motion, initiate (a device, reaction, circuit, etc)
   "activate the circuits";
   - actuate, trigger, set off, spark off, spark, trigger off, touch off
    
2. Make active or more active
   "activate an old file"
    
3. Make more adsorptive
   "activate a metal"
    
4. Aerate (sewage) so as to favour the growth of organisms that decompose organic matter
   - aerate
    
5. Make (substances) radioactive

Derived forms: activating, activated, activates

Type of: alter, change, initiate, modify, pioneer

Antonym: inactivate

Encyclopedia: Activate