reactant (noun) catalyst: something which incites activity
Sinonime: adjuvant, agitator, enzyme,
goad,
impetus,
impulse,
incendiary,
incentive, incitation, incitement,
motivation, radical stimulus, reactant, reactionary, spark plug,
spur, stimulant, synergist, wave maker
Antonime: block, blockage, preventer,
prevention