| Word root/prefix | Root Meaning | Words based on the Root |
| Endo | within, inside | Endotherm - a creature that can keep its inside temperature fairly constant Endocrine - relating to glands that secrete directly into the blood or lymph Endogamy - the custom to marry within one's clan, tribe etc. |
| Enn/i, anni | years | Bicentennial - of or relating to an age or period of 200 years Centennial - of or relating to an age or period of 100 years Perennial - lasting through many years. |
| Ep/i | on, upon, over, | Epidemic - the rapid spread of something negative Epilogue - a short speech delivered after a play Epicenter - the centre of an earthquake. |
| Equ/i | equal, equally | Equidistant - an equal distance from two points Equanimity - calm temperament, evenness of temper Equation - a statement of equality. |
| Erg/o | work | Ergonomics - study of the working environment Energy - the power to accomplish work Energetics - science that looks at energy and its transformation. |