| Term | Definition |
| DYS | bad ill difficult |
| Dysentery | inflammation of the large intestine usually caused by harmful microorganism in food or water |
| Dysfunction | abnormal functioning, as of an organ of the body |
| Dyslexia | impairment of the ability to read |
| Dyslogistic | expressing disapproval or harsh criticism; uncomplimentary |
| Dyspepsia | poor digestion; indigestion |
| Dysphagia | difficulty in swallowing |
| Dysphasia | speech difficulty resulting from brain injury |
| Dysphoria | sense of great unhappiness or dissatisfaction |
| Dystopia | imaginary place where living conditions are dreadful |
| Dystrophy | faulty nutrition |
| EU | good well advantageous |
| Eugenics | science dealing with improving the hereditary qualities (genes) of the human race |
| Eulogize | write or speak in praise of someone |
| Eupepsia | good digestion |
| Euphemism | substitution of a "good" expression for an unpleasant one. Example: passed away for death, or custodial engineer for janitor. |
| Euphonious | pleasing in sound |
| Euphoria | sense of great happiness or well-being |
| Euthanasia | The act or practice of ending the life of an individual suffering from a terminal illness or an incurable condition, as by lethal injection or the suspension of extraordinary medical treatment (literally "advantageous death") |
| Euthenics | science dealing with the improving living conditions |
| MACRO | large, long |
| MICRO | small, minute |
| Macrocosm | great world; universe |
| Macron | horizontal mark indicating the vowel over which it is placed is long |
| Macroscopic | large enough to be seen with the naked eye |
| Microbe | microorganism; microscopic living animal or plant |
| Microbicide | agent or substance that destroys microbes |
| Microdont | having small teeth |
| Microsecond | millionth of a second |
| Microwatt | millionth of a watt |