The effectiveness of ChatGPT as a lexical tool for English, compared with a bilingual dictionary and a monolingual learner's dictionary

Traditionally, language learners have relied on dictionaries when trying to read or write in a foreign language. However, new LLM-based chatbots may offer an alternative to traditional dictionaries as lexical tools. This study assesses the effectiveness of ChatGPT versus the monolingual Longman Dictionary of Contemporary English (LDOCE, 2024) and the bilingual Diki.pl (Diki.pl, 2024) online dictionaries in supporting English language learners in receptive and productive lexical tasks. With a sample of 166 university students at B2 to C1 proficiency levels and forty uncommon English phrasal verbs, we investigate whether a leading AI-driven chatbot, a high-quality learners' dictionary, or a popular free bilingual dictionary offers better support in accurately understanding and producing English. The results reveal ChatGPT to be more effective than either dictionary in production, and better than the monolingual dictionary, but not the bilingual dictionary, in reception.