An ENTHUSIAST is someone who is passionate and excited about a particular topic or activity. The term 'ENTHUSIAST' can be broken down into two crossword solutions: 'FIEND' (5 letters) and 'ZEALOT' (6 letters). A FIEND is an individual who is extremely passionate and devoted to something, while a ZEALOT is someone who is fanatically devoted to a cause or ideal. Both terms are often used to describe someone who is highly enthusiastic about a certain topic or activity.