| sierra para metales | hacksaw |
| sierraleonés | Sierra Leonean |
| sierras | mountain range |
| Sierras de Córdoba | Sierras de Córdoba |
| sierva | serf |
| siervo | serf |
| Siervo de Dios | Servant of God |
| siesta | doze |
| siete | seven |
| Siete Aguas | Siete Aguas |
| Siete Arcángeles | Seven Archangels |
| Siete años en el Tibet | Seven Years in Tibet |
| Siete bellezas | Seven Beauties |
| Siete Dioses de la Fortuna | Seven Lucky Gods |
| Siete días de mayo | Seven Days in May |
| Siete Maravillas de Portugal | Sete Maravilhas de Portugal |
| Siete Maravillas del Mundo | Seven Wonders of the Ancient World |
| Siete novias para siete hermanos | Seven Brides for Seven Brothers |
| siete pecados capitales | seven deadly sins |
| Siete preceptos de las naciones | Seven Laws of Noah |
| Siete Sabios | Seven Sages |
| Siete Sabios de Grecia | Seven Sages of Greece |
| siete virtudes | seven virtues |
| sievert | sievert |
| Sif | Sif |
| Sifax | Syphax |
| Sife | SIFE |
| sifilítica | syphilitic |
| sifilítico | syphilitic |
| Sifnos | Sifnos |
| sifón | siphon |
| siga | go ahead |
| Sigeberto I | Sigebert I |
| Sigeberto II | Sigebert II |
| Sigeberto III | Sigebert III |
| Siger de Brabant | Siger of Brabant |
| Sigerico | Sigeric |
| Sigerico el Serio | Sigeric the Serious |
| Sigfrido | Siegfried |
| Sigfrido de Suecia | Sigfrid of Sweden |
| Sigfried | Sigurd |
| Sigfried Held | Sigfried Held |
| SIGGRAPH | SIGGRAPH |
| Sighişoara | Sighişoara |
| sigilo | secretiveness |
| sigilo profesional | professional secrecy |
| sigilosamente | secretly |
| sigiloso | discreet |
| Sigirino | Sigirino |
| Sigiriya | Sigiriya |
| Sigismund Thalberg | Sigismond Thalberg |
| sigla | acronym |
