A historical document that was created at or near the time of the events studied, by a known person, for a known purpose(noun)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "primary source" in a sentence
"Armstrong name began illustriously The primary source used for the early history of the Armstrongs in Scotland is James L. Armstrong, Chronicles of theArmstrongs Salem, MA: Higginson Book Co., 1902."
"One group of historians, known in modern times as the vulgate tradition, used Cleitarchus as its primary source but supplemented his work with other authors."
"As cited in The Holy Blood and the Holy Grail, the primary source is a collection of just seven enigmatic documents lodged in the Bibliothèque Nationale in Paris, which are known as the Dossiers secrets secret dossiers12."