the original work (the original book, paper, or writing from which translations, citations, or adaptations are made).
この翻訳は原著に忠実で、意味がよく伝わっている。
This translation is faithful to the original work and conveys the meaning well.
研究者は原著を丁寧に読み込んだ。
The researcher read the original work carefully.
原著の表現は訳本とかなり異なることがある。
Expressions in the original work can sometimes differ considerably from the translated version.