[very common; 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 of redundant or superseded code.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”.