| Term | Definition | Pronunciation |
| zo/o | animal life | |
| zooplankton | Minute free-floating animal organisms which live in practically all natural waters. | |
| zyg/o | union, junction, yoke | |
| zygoma | Either of a pair of bones that form the prominent part of the CHEEK and contribute to the ORBIT on each side of the SKULL. | |
| zygomycosis | An acute, sometimes fatal fungal infection. | |
| zygote | The fertilized ovum resulting from the fusion of a male and a female gamete. | |
| zymo- | fermentation | |