Find 841 different ways to say ENTHUSIASTIC , along with antonyms, related words, and example sentences at Thesaurus.com. ENTHUSIASM definition: 1. a feeling of energetic interest in a particular subject or activity and an eagerness to be…. Learn more. Master the word " ENTHUSIASTIC " in English: definitions, translations, synonyms, pronunciations, examples, and grammar insights - all in one complete resource. The meaning of ENTHUSIASTIC is filled with or marked by enthusiasm. How to use enthusiastic in a sentence.