Encyclopedias, Almanacs, Transcripts, and Maps
- Sieve of Eratosthenes
- Sigmund Freud
- Sigmund Freud
- Sikhism, Bioethics in
- Silberhartz, Allen (1947-)
- Silbert, Maria (d. 1936)
- Silicic
- Silk Cotton Family (Bombacaceae)
- Silk Cotton Family (Bombacaceae)
- Silva, Edivaldo Oliveira (ca. 1930-1974)
- Silverfish and Fire Brats: Thysanura
- Silvester II, Pope (d. 1003)
- Silvestre Vélez de Escalante
- Siméon Denis Poisson
- Simmonite, William Joseph (ca. 1800-ca. 1862)
- Simon Antoine Jean Lhuilier
- Simon Kirwan Donaldson
- Simon Marius
- Simon of Genoa
- Simon Tunsted