1. Make active or more active
   "activate an old file"
    
2. Put in motion, initiate (a device, reaction, circuit, etc)
   "activate the circuits";
   - trip, actuate, trigger, set off, spark off, spark, trigger off, touch off
    
3. Make more adsorptive
   "activate a metal"
    
4. Aerate (sewage) so as to favour the growth of organisms that decompose organic matter
   "The treatment plant activated the wastewater to speed up the purification process";
   - aerate
    
5. Make (substances) radioactive
   "The scientists activated the isotope in the particle accelerator"

Derived forms: activated, activates, activating

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

Antonym: deactivate

Encyclopedia: Activate