| Siphonophorae | Siphonophora |
| Siphonophore | Siphonophora |
| Sipoo | Sipoo |
| Sippar | Sippar |
| Siproeta stelenes | Siproeta stelenes |
| Siptah | Siptah |
| Sipuncula | Sipuncula |
| Sipán | Sipán |
| Sir | Sir |
| Sir Ddinbych | Denbighshire |
| Sir Fynwy | Monmouthshire |
| Sir John Scarlett | John Scarlett |
| Sir Michael Berry | Michael Berry |
| Sir Mix a Lot | Sir Mix-a-Lot |
| Sir y Fflint | Flintshire |
| Sira | Sirah Rasul Allah |
| Siracide | Ben Sira |
| Siracusa | Siracusa |
| Sirajganj | Sirajganj |
| sire | Your Majesty |
| Sire Gauvain et le chevalier vert | Sir Gawain and the Green Knight |
| Sirenia | Sirenia |
| Sirenidae | Siren |
| Sirenomelia | Sirenomelia |
| Siret | Siret River |
| Sirhan Sirhan | Sirhan Sirhan |
| Siri Guru Granth Sahib | Guru Granth Sahib |
| Sirice | Pope Siricius |
| Siricidae | Horntail |
| Sirig | Sirig |
| Sirimavo Bandaranaike | Sirimavo Bandaranaike |
| Sirin | Sirin |
| Sirion | River Sirion |
| Sirius | Sirius |
| Sirius Black | Sirius Black |
| Sirmione | Sirmione |
| Sirmium | Sirmium |
| Sirnach | Sirnach |
| sirocco | sirocco |
| sirop | molasses |
| sirop antitussif | cough syrup |
| sirop contre la toux | cough syrup |
| sirop d'érable | maple syrup |
| Sirop de framboise | Raspberry juice |
| Sirop de maïs | High fructose corn syrup |
| Sirop de maïs à haute teneur en fructose | High fructose corn syrup |
| siropeux | syrupy |
| siroter | sip |
