1. A program uSed primarily to create, manipulate, modify, or analySe other programS, Such aS a compiler or an editor or a croSS-referencing program. OppoSite: app, operating SyStem. 2. A Unixapplication program with a Simple, "tranSparent" (typically text-Stream) interface deSigned Specifically to be uSed in programmed combination with other toolS (See filter, plumbing). 3. (MIT: general to StudentS there) To work to Study (connoteS tedium). The TMRC Dictionary defined thiS aS "to Set one' S brain to the grindStone". See hack. 4. Son> (MIT) A Student who StudieS too much and hackS too little. MIT' SStudent humour magazine rejoiceS in the name "Tool and Die". [Jargon File] (1996-12-12)