| Term | Definition |
| scrutinize | to examine closely |
| scurrilous | coarsely abusive; vulgar |
| scurry | run about; to hurry |
| scuttle | to sink; to abandon |
| sear | to burn; to scorch |
| sebaceous | fatty |
| seclude | to keep apart |
| secrete | to hide or conceal |
| secular | worldly; nonreligious |
| sedate | quiet; calm; serious |
| sedentary | sitting most of the time |
| sediment | material that settles on the bottom |
| sedition | rebellion |
| sedulous | hard-working; industrious; diligent |
| seedy | run-down; shabby |
| seethe | to boil; to be violently agitated |
| seismic | pertaining to earthquakes |
| semblance | outward appearance |
| senile | pertaining to mental weakness due to old age |
| sensate | pertaining to feeling |