1. bug-for-bug compatible Same as bug-compatible, with the additional implication that much tedious effort went into ensuring that each known bug was replicated. [Jargon File] buglix /buhg'liks/ Pejorative term referring to DEC's ULTRIX operating system in its earlier *severely* buggy versions. Still used to describe ULTRIX, but without nearly so much venom. Compare AIDX, HP-SUX, Nominal Semidestructor, Telerat, sun-stools. BUGSYS A programming system for pattern recognition and preparing animated films, for IBM 7094 and IBM 360. ["BUGSYS: A Programming System for Picture Processing - Not for Debugging", R.A. Ledley et al, CACM 92 Feb 1966].