| SIS | stiffly branching Old World annual with pale yellow flowers |
|---|---|
| SIS | perennial stellate and hairy herb with small yellow flowers of mountains of southern Europe |
| SIS | both extremely effortful and futile |
| SIS | of or relating to Sisyphus |
| SIS | (Greek legend) a king in ancient Greece who offended Zeus and whose punishment was to roll a huge boulder to the top of a steep hill |
| SIS | an arthropod family of the order Neuroptera that includes spongeflies |
| SIS | chiefly North American grasslike herbs |