High-overhead baroque code-intensive featureful, but costly. Especially used of communication protocols, language designs, and any sort of implEMentation in which maximum generality and/or ease of implEMentation has been pushed at the expense of mundane considerations such as speed, mEMory use and startup time. EMacs is a heavyweight editor X is an *extrEMely* heavyweight window systEM. This term isn' t pejorative, but one hacker' s heavyweight is another' s elephantine and a third' s monstrosity. Opposite: "lightweight". Usage: now borders on technical especially in the compound "heavyweight process". (1994-12-22)