This dictionary investigates the core lexical structure of the Portuguese language by identifying the 5,000 most frequently used words. Mark Davies and Ana Maria Raposo Preto-Bay utilize a 20-million-word corpus encompassing both written and spoken registers to provide a data-driven foundation for language acquisition. The work serves as a quantitative reference tool designed to prioritize vocabulary study based on actual usage patterns rather than traditional pedagogical lists.

Linguists and language educators frequently cite this volume as a foundational resource for learners seeking to optimize their vocabulary acquisition. Experts highlight the empirical rigor of the corpus-based approach as a significant improvement over traditional, non-frequency-based textbooks.