Idiomer is an evidence-first dictionary of idioms, proverbs, and slang in English and Vietnamese. It helps learners and curious readers discover what expressions mean, how they are used, and how sayings in one language relate to those in the other. Its searchable entries support Vietnamese searches with or without diacritics, while prioritizing exact accented matches, and can also be found by meaning.

Each entry includes a plain-language verification status, making clear whether an expression is attested, disputed, or still a candidate rather than presenting uncertain information as fact. Idiomer connects direct and near-equivalents across languages, and offers examples, themed collections, regional expressions, and learning resources such as lessons, quizzes, and practice activities. Users can browse English and Vietnamese dictionaries, explore topic lists and Bắc–Nam word comparisons, save expressions, or request a missing entry.

The site also publishes a blog and newsletter and provides an API. Idiomer’s definitions and examples are original editorial content, shared under a Creative Commons Attribution-ShareAlike 4. 0 license