Foamer is a term used to describe someone who is extremely enthusiastic about something, especially trains or public transportation. There are several synonyms for this word, including train enthusiast, railfan, and transit buff. These terms are often used interchangeably and refer to people who have a deep passion for all things related to trains or public transit. Other words that could be used as synonyms for foamer include aficionado, enthusiast, fanatic, and devotee. These terms all describe someone who is highly interested in a particular subject and is willing to invest a lot of time, money, and effort into pursuing that interest.