- shunt
- Shwachman syndrome
- Shwachman-Diamond syndrome
- sialic acid
- sialyl Tn-KLH
- sibling
- sickle cell anemia
- sickle cell disease
- side effect
- side-to-end coloanal anastomosis
- sideropenic dysphagia
- SIDS
- sigmoid colon
- sigmoidoscope
- sigmoidoscopy
- signal transduction
- signal transduction inhibitor
- signaling pathway
- signature molecule
- signet ring cell carcinoma
- significant
- SIL
- sildenafil
- silicon phthalocyanine 4
- silicone
- Silybum marianum
- silymarin
- simian virus 40
- simple mastectomy
- simple nephrectomy
- simple vulvectomy
- simulation
- single blind study
- single nucleotide polymorphism
- single-photon emission computed tomography
- Singulair
- sinus
- siplizumab
- sipuleucel-T
- sirolimus
- SIRS
- Sj
- SJG-136
- SK&F106615
- skeletal
- skeleton
- skin cancer
- skin conduction
- skin graft
- skin patch