What is Cruft?

cruft /kruhft/ [back-formation from {crufty}] 1. n. An unpleasant substance. The dust that gathers under your bed is cruft; the TMRC Dictionary correctly noted that attacking it with a broom only produces more. 2. n. The results of shoddy construction. 3. vt. [from `hand cruft', pun on `hand craft'] To write assembler code for something normally (and better) done by a compiler (see {hand-hacking}). 4. n. Excess; superfluous junk; used esp. of redundant or superseded code. 5. [University of Wisconsin] n. Cruft is to hackers as gaggle is to geese; that is, at UW one properly says "a cruft of hackers". This term is one of the oldest in the jargon and no one is sure of its etymology, but it is suggestive that there is a Cruft Hall at Harvard University which is part of the old physics building; it's said to have been the physics department's radar lab during WWII. To this day (early 1993) the windows appear to be full of random techno-junk. MIT or Lincoln Labs people may well have coined the term as a knock on the competition.

http://www.techfak.uni-bielefeld.de/~joern/jargon/cruft.HTML