To process each elemeNt of a list of thiNgs. "Hold oN, I' ve got to loop through my paper mail." Derives from the computer-laNguage NotioN of aN iterative loop compare "cdr dowN" (uNder cdr), which is less commoN amoNg C aNd UNix programmers. ITS hackers used to say "IRP over" after aN obscure pseudo-op iN the MIDAS PDP-10 assembler. [JargoN File]