Here are some examples of words derived from "certus":
* Certify: To declare something to be true or accurate.
* Certificate: A document that provides official proof of something.
* Certainty: The state of being sure of something.
* Assert: To state something confidently.
* Incert: To insert something. (The "in" prefix changes the meaning slightly)
* Concert: (Latin "concertare", meaning "to strive together")
The root "cert" can also be found in other languages, like Latin, where it retains the same meaning.