Exhibition Program

Science of Communication and Computation


How many words do you know?

Vocabulary size test, Reiwa edition


More than 20 years ago, NTT conducted psychological experiments to investigate word familiarity and thus construct a Japanese lexicon of about 77,000 words. This lexicon is still used in many fields. Now, we reinvestigated and reconstructed an unparalleled-scale Lexicon of 163,000 words through crowdsourcing. By applying careful screening, we succeeded in obtaining highly reliable results. This makes it possible to make comparisons with results of 20 years ago. Based on this, we created the Reiwa edition of a vocabulary-size estimation test. Furthermore, this lexicon allows us to estimate the vocabulary size appropriate for the present day. We are working on vocabulary-size investigations for a wide range of ages, including elementary school to high school students. In the future, we will investigate and analyze the relationship between vocabulary size, reading comprehension, and academic ability, aiming to achieve effective educational support.


  1. S. Fujita, T. Kobayashi, “Reexamination of word familiarity and comparison with past examination,” The 26th Annual Meeting of the Association for Natural Language Processing , pp. 1037 1040, 2020.
  2. S. Fujita, T. Kobayashi, T. Yamada, S. Sugawara, T. Arai, N. Arai, Vocabulary size of elementary, junior high and high school studentsand analysis of relationship with word familiarity,” The 26th Annual Meeting of the Association for Natural Language Processing , pp. 355358, 2020.



Sanae Fujita / Linguistic Intelligence Research Group, Innovative Communication Laboratory