stimulus (n.)

• activator
• aggravation
• agitation
• animation
• animator
• arousal
• arouser
• bait
• base
• basis
• boost
• bribe
• call
• carrot
• catalyst
• causation
• cause
• determinant
• determinative
• electrification
• element
• encouragement
• energizer
• etiology
• exacerbation
• exasperation
• excitation
• excitement
• exhilaration
• factor
• fillip
• fomentation
• galvanization
• goad
• ground
• grounds
• impetus
• impulse
• incentive
• incitation
• incitement
• inducement
• inflammation
• infuriation
• instigation
• interest
• invitation
• irritation
• life
• lure
• motivation
• motive
• occasion
• payment
• percentage
• perturbation
• principle
• profit
• propellant
• provocation
• push
• restorative
• reward
• spur
• stimulant
• stimulation
• stirring
• sweetener
• sweetening
• tonic
• urging