1. spath
    SPath is a library for running search queries against s-expressions, intended to match parts of them that the user needs
  2. spatial-trees
    spatial-trees is a set of dynamic index data structures for spatially-extended data
  3. speaker - Speech synthesis library
    Multiplatform Speech synthesis library wrapper for Common Lisp
  4. Special Slots
    A kind of pseudo-slot where the value is stored in a hidden symbol-value outside of the instance
  5. spinneret
    Common Lisp HTML5 generator
  6. SPLASH
    SPLASH is a library for displaying interactive splash screens containing warnings, notices and other information
  7. SPLIT-SEQUENCE
    SPLIT-SEQUENCE (formerly known as PARTITION) is a member of the Common Lisp Utilities family of programs, designed by community consensus
  8. SQL
    SQL (Structured Query Language) is a language for describing queries and updates against a relational database
  9. SQLite Lisp interface
    SQLite Lisp interface is an interface to the SQL database SQLite library
  10. SRFI
    Scheme Requests for Implementation (SRFI) are proposed language extensions to Scheme, but that doesn't stop people from implementing them for Common Lisp