| Word root/prefix | Root Meaning | Words based on the Root |
| Dem/o | people | Democracy - government of the people Demographic - the study of people Epidemic - spreading among people in a region |
| Di/plo | two, twice | Dichromatic - displaying two colors Diploma - a certificate, literally "a letter folded double" Dilemma - a situation that requires a choice between two alternatives. |
| Dict | speak | Contradict - to express the opposite of Prediction - a statement foretelling the future Dictate - to speak out loud for another person to write down. |
| Domin | master | Dominate - to be the master of Domineering - excessively controlling Predominate - to have more power than others |
| Ego | self | Egoistic - self-centered Alter ego - a higher aspect of oneself Egomania - excessive preoccupation with oneself. |