| catalyst(noun, activity, spur, goad, incentive) |
| adjuvant(noun, spur, goad, incentive, impetus) |
| agitator(noun, spur, goad, incentive, impetus) |
| enzyme(noun, spur, goad, incentive, impetus) |
| goad(noun, spur, incentive, impetus, promoter) |
| impulse(noun, spur, goad, incentive, impetus) |
| incendiary(noun, spur, goad, incentive, impetus) |
| incitation(noun, spur, goad, incentive, impetus) |
| incitement(noun, spur, goad, incentive, impetus) |
| motivation(noun, spur, goad, incentive, impetus) |
| radical stimulus(noun, expression, spur, goad, incentive) |
| reactionary(noun, spur, goad, incentive, impetus) |
| spark plug(noun, expression, spur, goad, incentive) |
| spur(noun, goad, incentive, impetus, promoter) |
| stimulant(noun, spur, goad, incentive, impetus) |
| synergist(noun, spur, goad, incentive, impetus) |
| wave maker(noun, expression, spur, goad, incentive) |
| accelerator |
| agent |
| bacterium |