A monolingual learner's dictionary (MLD) is designed to meet the reference needs of people learning a foreign language. MLDs are based on the premise that language-learners should progress from a bilingual dictionary to a monolingual one as they become more proficient in their target language, but that general-purpose dictionaries (aimed at native speakers) are inappropriate for their needs. Dictionaries for learners include information on grammar, usage, common errors, collocation, and pragmatics, which is largely missing from standard dictionaries, because native speakers tend to know these aspects of language intuitively. And while the definitions in standard dictionaries are often written in difficult language, those in an MLD use a simple and accessible defining vocabulary.