It comes from the Greek word "dis" meaning "twice" or "double."
Here are some examples of words with the prefix "di-":
* Dichotomy: A division into two parts
* Diatomic: Consisting of two atoms
* Digraph: Two letters that represent one sound
* Diploma: A document certifying completion of a course of study (originally given in duplicate)
* Disaccharide: A sugar consisting of two simple sugar molecules
* Dinosaur: "Terrible lizard" (from Greek "deinos" meaning "terrible" and "sauros" meaning "lizard")