source document

Short definition from Wiktionary

Noun

1. 1
   An original document that is subsequently copied, translated, or transcribed.
2. 2
   An original document or record that provides proof of activity that is summarized elsewhere (e.g. case notes, medical chart, diary entry, minutes of a meeting, etc.).
3. 3
   An original document or record that provides proof of activity that is summarized elsewhere (e.g. case notes, medical chart, diary entry, minutes of a meeting, etc.): A document that provides official notification of a credit or debit to an account, such as a bank statement, bill of sale, invoice, receipt, etc.