The original text or document from which translations or copies are made; the source/original version of a text.
翻訳は原文を忠実に訳すべきだ。
A translation should faithfully render the original text.
その古文書の原文は読みづらい。
The original of that ancient document is hard to read.
論文の原文と要約を提出してください。
Please submit the original paper and an abstract.