- special matrix
- special maximum resolution emulsion
- special-media map
- special medicine for military forces
- Special message of ChiangKai-shek to Chinese press
- special metric
- special mining method
- special mission
- special mission aircraft
- Special mission of Dong Biwu to the UN General Assembly
- special mortar
- special municipal organic law
- special net theory
- special offering
- Special Olympics
- Special Olympic World Games
- special operation
- special operator
- special optical fiber
- special orbital integral
- special ordering
- special ordinance
- special orthogonal group
- special orthogonal matrix
- special orthogonal polynomial