(FLI) /FLY/ A joke {assembly language} instruction first documented in the late 1970s in "The Hackers Dictionary". The FLI instruction was frequently referred to by engineers when minicomPUters such as the DEC PDP-8, PDP-11 and some early microcomPUters such as the IMSAI and Altair had dozens of front panel lights. "When the comPUter is about to do some long I/O operation, stick in a FLI so the accountants won' t think the machine has hung again." (2004-08-23)