An equatorial mounting in which the top end of a fork mounting is supported by a large circular bearing resembling a horseshoe. The design has great stability and has been used for large telescopes, such as the 200-inch (5-m) Hale Telescope at Palomar Observatory.
- Sputnik
- sputtering
- spyware
- Spörer, Gustav Friedrich Wilhelm (1822–95)
- Spörer minimum
- Spörer’s law
- SQA
- SQL
- SQL attack
- SQL injection
- SQL Server
- SQL server
- squalene
- squall
- squall line
- Squamata
- squamous epithelium
- square
- square array
- square(as a power)
- squared multiple correlation
- square-integrable
- Square Kilometre Array
- square-law detector
- square matrix