1. (

• trip ,
• actuate ,
• trigger ,
• activate ,
• set_off ,
• spark_off ,
• spark ,
• trigger_off ,
• touch_off

) put in motion or move to act; "trigger a reaction"; "actuate the circuits" ;

2. (

• activate

) make active or more active; "activate an old file" ;

3. (

• activate ,

) make more adsorptive; "activate a metal" ;

4. (

• activate ,
• aerate

) aerate (sewage) so as to favor the growth of organisms that decompose organic matter ;

5. (

• activate ,

) make (substances) radioactive ;

1. (

• activated

) (of sewage) treated with aeration and bacteria to aid decomposition ;

2. (

• activated ,
• excited

) (of e.g. a molecule) made reactive or more reactive ;

3. (

• activated

) rendered active; e.g. rendered radioactive or luminescent or photosensitive or conductive ;

4. (

• activated

) (military) set up and placed on active assignment; "a newly activated unit" ;