The term 'whetter' refers to someone or something that sharpens or stimulates a person's appetite or interest. There are several synonyms for this word, such as 'stimulant', 'appetizer', 'inciter', 'persuader', 'encourager', and 'instigator'. Each of these words refers to something that motivates or urges a person towards action or interest. For instance, a stimulant can be a chemical, substance, or activity that increases energy, attention, or alertness. Similarly, an appetizer can be a dish or food that serves to increase hunger or desire for the main course. Ultimately, the synonyms for whetter all share a common attribute in that they provide a boost of motivation, desire, or engagement.