Educational digitalization has played a significant role in reshaping EFL teaching and learning, particularly in enhancing vocabulary development. The integration of information and communication technologies (ICT) has fostered more personalized, interactive, and autonomous learning environments, enabling learners to actively engage with language beyond classroom boundaries. Within this context, online dictionaries have emerged as essential digital tools supporting lexical development and learner agency. Unlike traditional print dictionaries, online dictionaries function as dynamic, multifunctional platforms that provide immediate access to definitions, phonetic transcriptions, audio pronunciation, authentic usage examples, collocations, frequency data, and corpus-based information. These features enable learners to conceptualize vocabulary as a multidimensional construct encompassing form, meaning, and use rather than isolated word-meaning pairs. Empirical research consistently indicates that dictionary use positively impacts second language vocabulary development, with online dictionaries often proving more effective than print versions due to their accessibility, multimodal support, and increased consultation frequency.