1. n. A program used primarily to create, manipulate, modify,
or analyze other programs, such as a compiler or an editor or a
cross-referencing program.
Oppose app, operating system.
2. [UNIX] An application program with a simple, 'transparent'
(typically text-stream) interface designed specifically to be used
in programmed combination with other tools (see filter).
3. [MIT: general to students there] vi. To work; to study (connotes
tedium). The TMRC Dictionary defined this as "to set one's brain
to the grindstone".
See hack.
4. [MIT] n. A student who studies too much and hacks too little. (MIT's student humor
magazine rejoices in the name 'Tool and Die'.)