Definition of egregious in the Definitions.net dictionary. Meaning of egregious. What does egregious mean? Information and translations of egregious in the most comprehensive dictionary definitions resource on the web. Discover everything about the word "EGREGIOUS" in English: meanings, translations, synonyms, pronunciations, examples, and grammar insights - all in one comprehensive guide. EGREGIOUS meaning: 1. extremely bad in a way that is very noticeable: 2. extremely bad in a way that is very…. Learn more. Definition of egregious adjective in Oxford Advanced Learner's Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more.