| Abbreviation | Definition |
|---|---|
| SIM | Serving In Mission |
| SIMPLE | St. Ignatius Missionaries of Prayer Learning and Evangelization |
| SIMR | Surfing Is My Religion |
| SIMS | Students For International Mission Service |
| SINE | Systematic Integral New Evangelization |
| SING | Stars In Nature's Grace |
| SIS | Scripture In Song |
| SIS | Soul In Satanist |
| SISTER | Sisters In Scripture Teaching Encouraging Relationships |
| SISTERS | Saints In Service To Edify, Revive, and Support |
| SJ | Savior Jesus |
| SJ | Society of Jesus |
| SJ | St. Johns |
| SJ | St. Joseph |
| SJA | Saint John's Abbey of the Order of Saint Benedict |
| SJA | St. Joan of Arc Catholic Church |
| SJB | Saint John the Baptist |
| SJB | San Juan Bautista |
| SJB | St John Baptist |
| SJB | St John the Baptist |