nudger
/ˈnʌdʒər/Definitions
1. noun
A person or thing that nudges or has the effect of nudging someone or something.
“The government’s tax policy was seen as a nudger, encouraging people to save more.”
2. verb
To push or urge (someone or something) gently but firmly, often in order to bring about a particular action or decision.
“The teacher nudged the student gently to encourage him to answer the question.”