noun
product demonstrator
Refers to a person who demonstrates a product, typically in a store or at an event.
デパートでデモンストレーターが新しい掃除機の使い方を説明していた。
A demonstrator was explaining how to use the new vacuum cleaner at the department store.
noun
snowboard or ski instructor
Used in the context of snow sports to refer to an instructor who demonstrates techniques.
スキー場のデモンストレーターが華麗なターンを見せてくれた。
The ski instructor at the resort showed us a graceful turn.