2741. ulimyhmpqs
      ulimyhmpqs is an implementation of the Hypercube Multiple Polynomial Quadratic Sieve (HMPQS), an algorithm for the factorisation of large (up to about 110 digits, where the Number Field Sieve (NFS) algorithms become more efficient) integers
2742. uLisp
      uLisp is an embedded Lisp for microcontrollers, supporting Arduino, Adafruit M0/M4, Micro:bit, ESP8266/32, and RISC-V boards
2743. umlisp
      umlisp is an CLOS object-oriented interface to the Unified Medical Language System
2744. umpa-lumpa
      Umpa-Lumpa is a set of utilities used by armish and liards
2745. unicly
      UUIDs (Universally Unique Identifiers) v1-v5 per RFC 4122
2746. Unicode and Lisp
      Random ramblings on Unicode
2747. Unicode Support
      All contemporary Lisp implementations have reasonable Unicode support
2748. unification
      Libraries adding unification operations to Common Lisp
2749. unistd-stream
      A cl-stream stream using cffi-posix unistd semantics
2750. unit-conversion
      units is an extensive measuring unit (time/weight/distance/etc and many other physical units) conversion library

CLiki the common lisp wiki