| secular | Denoting attitudes, activities, or other things that have no religious or spiritual basis | |
| sedentary | Tending to spend much time seated; somewhat inactive | |
| sedulous | Showing dedication and diligence | |
| self-styled | Claiming to be something identified by one's own declaration without official recognition or confirmation | |
| semblance | The outward appearance or apparent form of something, especially when the reality is different | |
| sententious | Given to moralizing in a pompous or affected manner | |
| sentient | Able to perceive or feel things | |
| sequacious | Lacking independence or originality of thought | |
| sere | Dry or withered, especially used to describe vegetation | |
| serendipity | The occurrence of events by chance in a happy or beneficial way | |