| Word | Definitions | Synonyms |
|---|---|---|
| exoskeleton | (noun) the exterior protective or supporting structure or shell of many animals (especially invertebrates) including bony or horny parts such as nails or scales or hoofs | - |
| exosphere | (noun) the outermost atmospheric layer | - |
| exostosis | (noun) a benign outgrowth from a bone (usually covered with cartilage) | - |