from The American Heritage® Dictionary of the English Language, 4th Edition
- n. The branch of paleography that deals with the study of old official documents and determines their age and authenticity.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. The science of authenticating, dating, and interpreting old official documents.
from the GNU version of the Collaborative International Dictionary of English
- n. The science of diplomas, or the art of deciphering ancient writings, and determining their age, authenticity, etc.; paleography.
from The Century Dictionary and Cyclopedia
- n. The science of diplomas, or of ancient writings, literary and public documents, letters, decrees, charters, codicils, etc., which has for its object to decipher such instruments, or to ascertain their authenticity, their date, signatures, etc.
Probably from Italian or Ecclesiastical Latin diplomatica (Wiktionary)