Certes is an archaic adverb that was commonly used during medieval times to indicate certainty or truthfulness. It comes from the Latin word "certus" which means "certain" or "sure". While the use of the word certes has declined over the years, it continues to appear in literature, particularly in historical fiction or fantasy genres. Some synonyms for certes include certainly, surely, undoubtedly, truthfully, verily, assuredly, and indeed. These expressions all convey a level of conviction or affirmation in what has been said. Although certes may not be in common usage today, its counterparts have taken its position when used in modern conversation.