- Synorchidism 752.89
- Synorchism 752.89
- Synostosis (congenital) 756.59
- Synovial - see condition
- Synovioma (M9040/3) - see also Neoplasm, connective tissue, malignant
- Synoviosarcoma (M9040/3) - see Neoplasm, connective tissue, malignant
- Synovitis (see also Tenosynovitis) 727.00
- Syphilide 091.3
- Syphilis, syphilitic (acquired) 097.9
- Syphiloma 095.9
- Syphilophobia 300.29
- Syringadenoma (M8400/0) - see also Neoplasm, skin, benign
- Syringobulbia 336.0
- Syringocarcinoma (M8400/3) - see Neoplasm, skin, malignant
- Syringocystadenoma (M8400/0) - see also Neoplasm, skin, benign
- Syringocystoma (M8407/0) - see Neoplasm, skin, benign
- Syringoma (M8407/0) - see also Neoplasm, skin, benign
- Syringomyelia 336.0
- Syringomyelitis 323.9
- Syringomyelocele (see also Spina bifida) 741.9
- Syringopontia 336.0
- System, systemic - see also condition
