Using morphologically annotated corpora of modern and contemporary Japanese (“Corpus of Historical Japanese” [CHJ] Meiji-Taishō Series I – Magazines and “Balanced Corpus of Contemporary Written Japanese” [BCCWJ]), I conducted a survey and analysis of the differences between Sino-Japanese words. By examining the frequency and coverage of individual words, the following three points were clarified regarding the 55,000 words utilized in the modern and contemporary eras:
1) Altogether, 50,000 words are used in CHJ and BCCWJ, and 22,400 words are employed in both corpora. About 19,400 words (e.g. “発兌,” “状師,” “英人,” “征清,” “邦国”) are used only in the modern era, and 7,700 words (e.g. “支援,” “介護,” “強化,” “本格,” “展示”) are used only in the contemporary era, indicating that Sino-Japanese vocabulary is larger in the modern era than the contemporary era.
2) A total of 42% of the common words (e.g. “問題,” “世界,” “以上,” “研究,” “経済”) in CHJ and BCCWJ have no significant differences. However, the other 31% (e.g. “今日,” “吾人,” “憲政,” “列国,” “世人”) decreased, and 27% (e.g. “時間,” “意味,” “可能,” “企業,” “利用”) increased significantly. Thus, Sino-Japanese vocabulary changed from the modern era to the contemporary era.
3) These diachronic changes are caused by historical context, consolidation of synonyms, stylistic changes, and changes in the themes of texts.